[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[gawk-diffs] [SCM] gawk branch, gawk-4.1-stable, updated. gawk-4.1.0-721
|
From: |
Arnold Robbins |
|
Subject: |
[gawk-diffs] [SCM] gawk branch, gawk-4.1-stable, updated. gawk-4.1.0-721-gab40bfa |
|
Date: |
Fri, 19 Jun 2015 09:21:01 +0000 |
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "gawk".
The branch, gawk-4.1-stable has been updated
via ab40bfaf0bab83d15fee1082e6fa4bdd775f7021 (commit)
via 511c52f994faa82ce7595759c17b6ea7bc530288 (commit)
from c143b9ed4402a67e02ed13befb5999f32f8afc5f (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
http://git.sv.gnu.org/cgit/gawk.git/commit/?id=ab40bfaf0bab83d15fee1082e6fa4bdd775f7021
commit ab40bfaf0bab83d15fee1082e6fa4bdd775f7021
Author: Arnold D. Robbins <address@hidden>
Date: Fri Jun 19 12:20:40 2015 +0300
Update extract.awk.
diff --git a/awklib/ChangeLog b/awklib/ChangeLog
index f0e82f5..791c25f 100644
--- a/awklib/ChangeLog
+++ b/awklib/ChangeLog
@@ -1,3 +1,8 @@
+2015-06-19 Arnold D. Robbins <address@hidden>
+
+ * extract.awk: Sync with current version in the doc. Thanks to
+ Antonio Columbo for pointing this out.
+
2015-05-19 Arnold D. Robbins <address@hidden>
* 4.1.3: Release tar ball made.
diff --git a/awklib/extract.awk b/awklib/extract.awk
index 1b052e7..2662574 100644
--- a/awklib/extract.awk
+++ b/awklib/extract.awk
@@ -1,16 +1,14 @@
-# extract.awk --- extract files and run programs
-# from texinfo files
+# extract.awk --- extract files and run programs from Texinfo files
#
-# Arnold Robbins, address@hidden, Public Domain
+# Arnold Robbins, address@hidden, Public Domain
# May 1993
# Revised September 2000
BEGIN { IGNORECASE = 1 }
-/address@hidden(omment)?[ \t]+system/ \
-{
+/address@hidden(omment)?[ \t]+system/ {
if (NF < 3) {
- e = (FILENAME ":" FNR)
+ e = ("extract: " FILENAME ":" FNR)
e = (e ": badly formed `system' line")
print e > "/dev/stderr"
next
@@ -19,15 +17,14 @@ BEGIN { IGNORECASE = 1 }
$2 = ""
stat = system($0)
if (stat != 0) {
- e = (FILENAME ":" FNR)
+ e = ("extract: " FILENAME ":" FNR)
e = (e ": warning: system returned " stat)
print e > "/dev/stderr"
}
}
-/address@hidden(omment)?[ \t]+file/ \
-{
+/address@hidden(omment)?[ \t]+file/ {
if (NF != 3) {
- e = (FILENAME ":" FNR ": badly formed `file' line")
+ e = ("extract: " FILENAME ":" FNR ": badly formed `file' line")
print e > "/dev/stderr"
next
}
@@ -65,8 +62,8 @@ BEGIN { IGNORECASE = 1 }
}
function unexpected_eof()
{
- printf("%s:%d: unexpected EOF or error\n",
- FILENAME, FNR) > "/dev/stderr"
+ printf("extract: %s:%d: unexpected EOF or error\n",
+ FILENAME, FNR) > "/dev/stderr"
exit 1
}
http://git.sv.gnu.org/cgit/gawk.git/commit/?id=511c52f994faa82ce7595759c17b6ea7bc530288
commit 511c52f994faa82ce7595759c17b6ea7bc530288
Author: Arnold D. Robbins <address@hidden>
Date: Fri Jun 19 12:19:53 2015 +0300
Minor doc fix.
diff --git a/awklib/eg/network/coreserv.awk b/awklib/eg/network/coreserv.awk
index 348568e..a5c8b1e 100644
--- a/awklib/eg/network/coreserv.awk
+++ b/awklib/eg/network/coreserv.awk
@@ -1,7 +1,7 @@
# CGI Library and core of a web server
#
# Juergen Kahrs, address@hidden
-# with Arnold Robbins, address@hidden
+# with Arnold Robbins, address@hidden
# September 2000
# Global arrays
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 6e4c40b..113f7b6 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,7 @@
+2015-06-19 Arnold D. Robbins <address@hidden>
+
+ * gawkinet.info: Fix an old address@hidden
+
2015-06-17 Andrew J. Schorr <address@hidden>
* gawktexi.in: Document inplace shortcomings -- it does not preserve
diff --git a/doc/gawkinet.info b/doc/gawkinet.info
index d726be0..81837aa 100644
--- a/doc/gawkinet.info
+++ b/doc/gawkinet.info
@@ -1,12 +1,7 @@
-This is gawkinet.info, produced by makeinfo version 4.13 from
+This is gawkinet.info, produced by makeinfo version 5.2 from
gawkinet.texi.
-INFO-DIR-SECTION Network applications
-START-INFO-DIR-ENTRY
-* Gawkinet: (gawkinet). TCP/IP Internetworking With `gawk'.
-END-INFO-DIR-ENTRY
-
- This is Edition 1.3 of `TCP/IP Internetworking with `gawk'', for the
+This is Edition 1.3 of 'TCP/IP Internetworking with 'gawk'', for the
4.0.0 (or later) version of the GNU implementation of AWK.
@@ -27,10 +22,14 @@ texts being (a) (see below), and with the Back-Cover Texts
being (b)
b. "You have the freedom to copy and modify this GNU manual. Buying
copies from the FSF supports it in developing GNU and promoting
software freedom."
+INFO-DIR-SECTION Network applications
+START-INFO-DIR-ENTRY
+* Gawkinet: (gawkinet). TCP/IP Internetworking With 'gawk'.
+END-INFO-DIR-ENTRY
- This file documents the networking features in GNU `awk'.
+ This file documents the networking features in GNU 'awk'.
- This is Edition 1.3 of `TCP/IP Internetworking with `gawk'', for the
+ This is Edition 1.3 of 'TCP/IP Internetworking with 'gawk'', for the
4.0.0 (or later) version of the GNU implementation of AWK.
@@ -58,10 +57,10 @@ File: gawkinet.info, Node: Top, Next: Preface, Prev:
(dir), Up: (dir)
General Introduction
********************
-This file documents the networking features in GNU Awk (`gawk') version
+This file documents the networking features in GNU Awk ('gawk') version
4.0 and later.
- This is Edition 1.3 of `TCP/IP Internetworking with `gawk'', for the
+ This is Edition 1.3 of 'TCP/IP Internetworking with 'gawk'', for the
4.0.0 (or later) version of the GNU implementation of AWK.
@@ -100,7 +99,7 @@ texts being (a) (see below), and with the Back-Cover Texts
being (b)
* Basic Protocols:: The basic protocols.
* Ports:: The idea behind ports.
* Making Connections:: Making TCP/IP connections.
-* Gawk Special Files:: How to do `gawk' networking.
+* Gawk Special Files:: How to do 'gawk' networking.
* Special File Fields:: The fields in the special file name.
* Comparing Protocols:: Differences between the protocols.
* File /inet/tcp:: The TCP special file.
@@ -135,28 +134,28 @@ Preface
*******
In May of 1997, Ju"rgen Kahrs felt the need for network access from
-`awk', and, with a little help from me, set about adding features to do
-this for `gawk'. At that time, he wrote the bulk of this Info file.
+'awk', and, with a little help from me, set about adding features to do
+this for 'gawk'. At that time, he wrote the bulk of this Info file.
- The code and documentation were added to the `gawk' 3.1 development
+ The code and documentation were added to the 'gawk' 3.1 development
tree, and languished somewhat until I could finally get down to some
-serious work on that version of `gawk'. This finally happened in the
+serious work on that version of 'gawk'. This finally happened in the
middle of 2000.
Meantime, Ju"rgen wrote an article about the Internet special files
-and `|&' operator for `Linux Journal', and made a networking patch for
-the production versions of `gawk' available from his home page. In
-August of 2000 (for `gawk' 3.0.6), this patch also made it to the main
-GNU `ftp' distribution site.
+and '|&' operator for 'Linux Journal', and made a networking patch for
+the production versions of 'gawk' available from his home page. In
+August of 2000 (for 'gawk' 3.0.6), this patch also made it to the main
+GNU 'ftp' distribution site.
- For release with `gawk', I edited Ju"rgen's prose for English
-grammar and style, as he is not a native English speaker. I also
-rearranged the material somewhat for what I felt was a better order of
-presentation, and (re)wrote some of the introductory material.
+ For release with 'gawk', I edited Ju"rgen's prose for English grammar
+and style, as he is not a native English speaker. I also rearranged the
+material somewhat for what I felt was a better order of presentation,
+and (re)wrote some of the introductory material.
- The majority of this document and the code are his work, and the
-high quality and interesting ideas speak for themselves. It is my hope
-that these features will be of significant value to the `awk' community.
+ The majority of this document and the code are his work, and the high
+quality and interesting ideas speak for themselves. It is my hope that
+these features will be of significant value to the 'awk' community.
Arnold Robbins
@@ -170,16 +169,16 @@ File: gawkinet.info, Node: Introduction, Next: Using
Networking, Prev: Prefac
*********************
This major node provides a (necessarily) brief introduction to computer
-networking concepts. For many applications of `gawk' to TCP/IP
+networking concepts. For many applications of 'gawk' to TCP/IP
networking, we hope that this is enough. For more advanced tasks, you
will need deeper background, and it may be necessary to switch to
lower-level programming in C or C++.
- There are two real-life models for the way computers send messages
-to each other over a network. While the analogies are not perfect,
-they are close enough to convey the major concepts. These two models
-are the phone system (reliable byte-stream communications), and the
-postal system (best-effort datagrams).
+ There are two real-life models for the way computers send messages to
+each other over a network. While the analogies are not perfect, they
+are close enough to convey the major concepts. These two models are the
+phone system (reliable byte-stream communications), and the postal
+system (best-effort datagrams).
* Menu:
@@ -199,19 +198,19 @@ When you make a phone call, the following steps occur:
1. You dial a number.
2. The phone system connects to the called party, telling them there
- is an incoming call. (Their phone rings.)
+ is an incoming call. (Their phone rings.)
3. The other party answers the call, or, in the case of a computer
network, refuses to answer the call.
- 4. Assuming the other party answers, the connection between you is
- now a "duplex" (two-way), "reliable" (no data lost), sequenced
- (data comes out in the order sent) data stream.
+ 4. Assuming the other party answers, the connection between you is now
+ a "duplex" (two-way), "reliable" (no data lost), sequenced (data
+ comes out in the order sent) data stream.
5. You and your friend may now talk freely, with the phone system
- moving the data (your voices) from one end to the other. From
- your point of view, you have a direct end-to-end connection with
- the person on the other end.
+ moving the data (your voices) from one end to the other. From your
+ point of view, you have a direct end-to-end connection with the
+ person on the other end.
The same steps occur in a duplex reliable computer networking
connection. There is considerably more overhead in setting up the
@@ -234,16 +233,15 @@ following.
3. Each envelope may travel a different route to its destination.
- 4. The envelopes may arrive in a different order from the one in
- which they were sent.
+ 4. The envelopes may arrive in a different order from the one in which
+ they were sent.
- 5. One or more may get lost in the mail. (Although, fortunately,
- this does not occur very often.)
+ 5. One or more may get lost in the mail. (Although, fortunately, this
+ does not occur very often.)
6. In a computer network, one or more "packets" may also arrive
multiple times. (This doesn't happen with the postal system!)
-
The important characteristics of datagram communications, like those
of the postal system are thus:
@@ -255,8 +253,8 @@ of the postal system are thus:
* Delivery is _not_ sequenced; packets may arrive out of order,
and/or multiple times.
- * Unlike the phone system, overhead is considerably lower. It is
- not necessary to set up the call first.
+ * Unlike the phone system, overhead is considerably lower. It is not
+ necessary to set up the call first.
The price the user pays for the lower overhead of datagram
communications is exactly the lower reliability; it is often necessary
@@ -293,45 +291,45 @@ File: gawkinet.info, Node: Basic Protocols, Next:
Ports, Prev: The TCP/IP Pro
----------------------------------
IP
- The Internet Protocol. This protocol is almost never used
- directly by applications. It provides the basic packet delivery
- and routing infrastructure of the Internet. Much like the phone
- company's switching centers or the Post Office's trucks, it is not
- of much day-to-day interest to the regular user (or programmer).
- It happens to be a best effort datagram protocol. In the early
+ The Internet Protocol. This protocol is almost never used directly
+ by applications. It provides the basic packet delivery and routing
+ infrastructure of the Internet. Much like the phone company's
+ switching centers or the Post Office's trucks, it is not of much
+ day-to-day interest to the regular user (or programmer). It
+ happens to be a best effort datagram protocol. In the early
twenty-first century, there are two versions of this protocol in
use:
- IPv4
+ IPv4
The original version of the Internet Protocol, with 32-bit
addresses, on which most of the current Internet is based.
- IPv6
+ IPv6
The "next generation" of the Internet Protocol, with 128-bit
addresses. This protocol is in wide use in certain parts of
the world, but has not yet replaced IPv4.(1)
Versions of the other protocols that sit "atop" IP exist for both
- IPv4 and IPv6. However, as the IPv6 versions are fundamentally the
- same as the original IPv4 versions, we will not distinguish
- further between them.
+ IPv4 and IPv6. However, as the IPv6 versions are fundamentally the
+ same as the original IPv4 versions, we will not distinguish further
+ between them.
UDP
The User Datagram Protocol. This is a best effort datagram
- protocol. It provides a small amount of extra reliability over
- IP, and adds the notion of "ports", described in *note TCP and UDP
+ protocol. It provides a small amount of extra reliability over IP,
+ and adds the notion of "ports", described in *note TCP and UDP
Ports: Ports.
TCP
The Transmission Control Protocol. This is a duplex, reliable,
sequenced byte-stream protocol, again layered on top of IP, and
also providing the notion of ports. This is the protocol that you
- will most likely use when using `gawk' for network programming.
+ will most likely use when using 'gawk' for network programming.
All other user-level protocols use either TCP or UDP to do their
basic communications. Examples are SMTP (Simple Mail Transfer
Protocol), FTP (File Transfer Protocol), and HTTP (HyperText Transfer
-Protocol).
+Protocol).
---------- Footnotes ----------
@@ -344,14 +342,14 @@ File: gawkinet.info, Node: Ports, Prev: Basic
Protocols, Up: The TCP/IP Proto
-----------------------
In the postal system, the address on an envelope indicates a physical
-location, such as a residence or office building. But there may be
-more than one person at the location; thus you have to further quantify
-the recipient by putting a person or company name on the envelope.
+location, such as a residence or office building. But there may be more
+than one person at the location; thus you have to further quantify the
+recipient by putting a person or company name on the envelope.
In the phone system, one phone number may represent an entire
company, in which case you need a person's extension number in order to
reach that individual directly. Or, when you call a home, you have to
-say, "May I please speak to ..." before talking to the person directly.
+say, "May I please speak to ..." before talking to the person directly.
IP networking provides the concept of addressing. An IP address
represents a particular computer, but no more. In order to reach the
@@ -361,11 +359,10 @@ Internet Protocol suite, this is done with "port
numbers", which
represent the services, much like an extension number used with a phone
number.
- Port numbers are 16-bit integers. Unix and Unix-like systems
-reserve ports below 1024 for "well known" services, such as SMTP, FTP,
-and HTTP. Numbers 1024 and above may be used by any application,
-although there is no promise made that a particular port number is
-always available.
+ Port numbers are 16-bit integers. Unix and Unix-like systems reserve
+ports below 1024 for "well known" services, such as SMTP, FTP, and HTTP.
+Numbers 1024 and above may be used by any application, although there is
+no promise made that a particular port number is always available.
File: gawkinet.info, Node: Making Connections, Prev: The TCP/IP Protocols,
Up: Introduction
@@ -374,12 +371,12 @@ File: gawkinet.info, Node: Making Connections, Prev:
The TCP/IP Protocols, Up
====================================================
Two terms come up repeatedly when discussing networking: "client" and
-"server". For now, we'll discuss these terms at the "connection
-level", when first establishing connections between two processes on
-different systems over a network. (Once the connection is established,
-the higher level, or "application level" protocols, such as HTTP or
-FTP, determine who is the client and who is the server. Often, it
-turns out that the client and server are the same in both roles.)
+"server". For now, we'll discuss these terms at the "connection level",
+when first establishing connections between two processes on different
+systems over a network. (Once the connection is established, the higher
+level, or "application level" protocols, such as HTTP or FTP, determine
+who is the client and who is the server. Often, it turns out that the
+client and server are the same in both roles.)
The "server" is the system providing the service, such as the web
server or email server. It is the "host" (system) which is _connected
@@ -389,34 +386,33 @@ building to answer the phone(1), the server process
(usually) has to be
started first and be waiting for a connection.
The "client" is the system requesting the service. It is the system
-_initiating the connection_ in a transaction. (Just as when you pick
-up the phone to call an office or store.)
-
- In the TCP/IP framework, each end of a connection is represented by
-a pair of (ADDRESS, PORT) pairs. For the duration of the connection,
-the ports in use at each end are unique, and cannot be used
-simultaneously by other processes on the same system. (Only after
-closing a connection can a new one be built up on the same port. This
-is contrary to the usual behavior of fully developed web servers which
-have to avoid situations in which they are not reachable. We have to
-pay this price in order to enjoy the benefits of a simple communication
-paradigm in `gawk'.)
+_initiating the connection_ in a transaction. (Just as when you pick up
+the phone to call an office or store.)
+
+ In the TCP/IP framework, each end of a connection is represented by a
+pair of (ADDRESS, PORT) pairs. For the duration of the connection, the
+ports in use at each end are unique, and cannot be used simultaneously
+by other processes on the same system. (Only after closing a connection
+can a new one be built up on the same port. This is contrary to the
+usual behavior of fully developed web servers which have to avoid
+situations in which they are not reachable. We have to pay this price
+in order to enjoy the benefits of a simple communication paradigm in
+'gawk'.)
Furthermore, once the connection is established, communications are
-"synchronous".(2) I.e., each end waits on the other to finish
-transmitting, before replying. This is much like two people in a phone
+"synchronous".(2) I.e., each end waits on the other to finish
+transmitting, before replying. This is much like two people in a phone
conversation. While both could talk simultaneously, doing so usually
doesn't work too well.
In the case of TCP, the synchronicity is enforced by the protocol
when sending data. Data writes "block" until the data have been
-received on the other end. For both TCP and UDP, data reads block
-until there is incoming data waiting to be read. This is summarized in
-the following table, where an "X" indicates that the given action
-blocks.
+received on the other end. For both TCP and UDP, data reads block until
+there is incoming data waiting to be read. This is summarized in the
+following table, where an "X" indicates that the given action blocks.
TCP X X
-UDP X
+UDP X
---------- Footnotes ----------
@@ -429,38 +425,38 @@ receiving a "there's no data" error return.
File: gawkinet.info, Node: Using Networking, Next: Some Applications and
Techniques, Prev: Introduction, Up: Top
-2 Networking With `gawk'
+2 Networking With 'gawk'
************************
-The `awk' programming language was originally developed as a
+The 'awk' programming language was originally developed as a
pattern-matching language for writing short programs to perform data
-manipulation tasks. `awk''s strength is the manipulation of textual
+manipulation tasks. 'awk''s strength is the manipulation of textual
data that is stored in files. It was never meant to be used for
networking purposes. To exploit its features in a networking context,
it's necessary to use an access mode for network connections that
resembles the access of files as closely as possible.
- `awk' is also meant to be a prototyping language. It is used to
+ 'awk' is also meant to be a prototyping language. It is used to
demonstrate feasibility and to play with features and user interfaces.
-This can be done with file-like handling of network connections.
-`gawk' trades the lack of many of the advanced features of the TCP/IP
-family of protocols for the convenience of simple connection handling.
-The advanced features are available when programming in C or Perl. In
-fact, the network programming in this major node is very similar to
-what is described in books such as `Internet Programming with Python',
-`Advanced Perl Programming', or `Web Client Programming with Perl'.
+This can be done with file-like handling of network connections. 'gawk'
+trades the lack of many of the advanced features of the TCP/IP family of
+protocols for the convenience of simple connection handling. The
+advanced features are available when programming in C or Perl. In fact,
+the network programming in this major node is very similar to what is
+described in books such as 'Internet Programming with Python', 'Advanced
+Perl Programming', or 'Web Client Programming with Perl'.
However, you can do the programming here without first having to
learn object-oriented ideology; underlying languages such as Tcl/Tk,
Perl, Python; or all of the libraries necessary to extend these
languages before they are ready for the Internet.
- This major node demonstrates how to use the TCP protocol. The UDP
+ This major node demonstrates how to use the TCP protocol. The UDP
protocol is much less important for most users.
* Menu:
-* Gawk Special Files:: How to do `gawk' networking.
+* Gawk Special Files:: How to do 'gawk' networking.
* TCP Connecting:: Making a TCP connection.
* Troubleshooting:: Troubleshooting TCP/IP connections.
* Interacting:: Interacting with a service.
@@ -476,20 +472,20 @@ protocol is much less important for most users.
File: gawkinet.info, Node: Gawk Special Files, Next: TCP Connecting, Prev:
Using Networking, Up: Using Networking
-2.1 `gawk''s Networking Mechanisms
+2.1 'gawk''s Networking Mechanisms
==================================
-The `|&' operator for use in communicating with a "coprocess" is
+The '|&' operator for use in communicating with a "coprocess" is
described in *note Two-way Communications With Another Process:
(gawk)Two-way I/O. It shows how to do two-way I/O to a separate
-process, sending it data with `print' or `printf' and reading data with
-`getline'. If you haven't read it already, you should detour there to
+process, sending it data with 'print' or 'printf' and reading data with
+'getline'. If you haven't read it already, you should detour there to
do so.
- `gawk' transparently extends the two-way I/O mechanism to simple
+ 'gawk' transparently extends the two-way I/O mechanism to simple
networking through the use of special file names. When a "coprocess"
that matches the special files we are about to describe is started,
-`gawk' creates the appropriate network connection, and then two-way I/O
+'gawk' creates the appropriate network connection, and then two-way I/O
proceeds as usual.
At the C, C++, and Perl level, networking is accomplished via
@@ -498,8 +494,8 @@ developed at the University of California at Berkeley that
is now used
almost universally for TCP/IP networking. Socket level programming,
while fairly straightforward, requires paying attention to a number of
details, as well as using binary data. It is not well-suited for use
-from a high-level language like `awk'. The special files provided in
-`gawk' hide the details from the programmer, making things much simpler
+from a high-level language like 'awk'. The special files provided in
+'gawk' hide the details from the programmer, making things much simpler
and easier to use.
The special file name for network access is made up of several
@@ -524,56 +520,56 @@ File: gawkinet.info, Node: Special File Fields, Next:
Comparing Protocols, Pr
This node explains the meaning of all the other fields, as well as the
range of values and the defaults. All of the fields are mandatory. To
let the system pick a value, or if the field doesn't apply to the
-protocol, specify it as `0':
+protocol, specify it as '0':
NET-TYPE
- This is one of `inet4' for IPv4, `inet6' for IPv6, or `inet' to
- use the system default (which is likely to be IPv4). For the rest
- of this document, we will use the generic `/inet' in our
- descriptions of how `gawk''s networking works.
+ This is one of 'inet4' for IPv4, 'inet6' for IPv6, or 'inet' to use
+ the system default (which is likely to be IPv4). For the rest of
+ this document, we will use the generic '/inet' in our descriptions
+ of how 'gawk''s networking works.
PROTOCOL
Determines which member of the TCP/IP family of protocols is
- selected to transport the data across the network. There are two
- possible values (always written in lowercase): `tcp' and `udp'.
+ selected to transport the data across the network. There are two
+ possible values (always written in lowercase): 'tcp' and 'udp'.
The exact meaning of each is explained later in this node.
LOCALPORT
Determines which port on the local machine is used to communicate
- across the network. Application-level clients usually use `0' to
+ across the network. Application-level clients usually use '0' to
indicate they do not care which local port is used--instead they
- specify a remote port to connect to. It is vital for
- application-level servers to use a number different from `0' here
+ specify a remote port to connect to. It is vital for
+ application-level servers to use a number different from '0' here
because their service has to be available at a specific publicly
- known port number. It is possible to use a name from
- `/etc/services' here.
+ known port number. It is possible to use a name from
+ '/etc/services' here.
HOSTNAME
Determines which remote host is to be at the other end of the
- connection. Application-level servers must fill this field with a
- `0' to indicate their being open for all other hosts to connect to
+ connection. Application-level servers must fill this field with a
+ '0' to indicate their being open for all other hosts to connect to
them and enforce connection level server behavior this way. It is
not possible for an application-level server to restrict its
availability to one remote host by entering a host name here.
- Application-level clients must enter a name different from `0'.
- The name can be either symbolic (e.g., `jpl-devvax.jpl.nasa.gov')
- or numeric (e.g., `128.149.1.143').
+ Application-level clients must enter a name different from '0'.
+ The name can be either symbolic (e.g., 'jpl-devvax.jpl.nasa.gov')
+ or numeric (e.g., '128.149.1.143').
REMOTEPORT
Determines which port on the remote machine is used to communicate
- across the network. For `/inet/tcp' and `/inet/udp',
- application-level clients _must_ use a number other than `0' to
+ across the network. For '/inet/tcp' and '/inet/udp',
+ application-level clients _must_ use a number other than '0' to
indicate to which port on the remote machine they want to connect.
- Application-level servers must not fill this field with a `0'.
+ Application-level servers must not fill this field with a '0'.
Instead they specify a local port to which clients connect. It is
- possible to use a name from `/etc/services' here.
+ possible to use a name from '/etc/services' here.
Experts in network programming will notice that the usual
client/server asymmetry found at the level of the socket API is not
-visible here. This is for the sake of simplicity of the high-level
-concept. If this asymmetry is necessary for your application, use
-another language. For `gawk', it is more important to enable users to
-write a client program with a minimum of code. What happens when first
+visible here. This is for the sake of simplicity of the high-level
+concept. If this asymmetry is necessary for your application, use
+another language. For 'gawk', it is more important to enable users to
+write a client program with a minimum of code. What happens when first
accessing a network connection is seen in the following pseudocode:
if ((name of remote host given) && (other side accepts connection)) {
@@ -589,24 +585,25 @@ accessing a network connection is seen in the following
pseudocode:
}
The exact behavior of this algorithm depends on the values of the
-fields of the special file name. When in doubt, *note
-table-inet-components:: gives you the combinations of values and their
-meaning. If this table is too complicated, focus on the three lines
-printed in *bold*. All the examples in *note Networking With `gawk':
+fields of the special file name. When in doubt, *note Table 2.1:
+table-inet-components. gives you the combinations of values and their
+meaning. If this table is too complicated, focus on the three lines
+printed in *bold*. All the examples in *note Networking With 'gawk':
Using Networking, use only the patterns printed in bold letters.
-PROTOCOL LOCAL PORT HOST NAME REMOTE RESULTING CONNECTION-LEVEL
- PORT BEHAVIOR
-------------------------------------------------------------------------------
-*tcp* *0* *x* *x* *Dedicated client, fails if
+PROTOCOL LOCAL HOST NAME REMOTE RESULTING CONNECTION-LEVEL
+ PORT PORT BEHAVIOR
+------------------------------------------------------------------------------
+*tcp* *0* *x* *x* *Dedicated client, fails if
immediately connecting to a
- server on the
- other side fails*
+ server on the other side
+ fails*
udp 0 x x Dedicated client
-*tcp, udp* *x* *x* *x* *Client, switches to
- dedicated server if
+*tcp, *x* *x* *x* *Client, switches to
+udp* dedicated server if
necessary*
-*tcp, udp* *x* *0* *0* *Dedicated server*
+*tcp, *x* *0* *0* *Dedicated server*
+udp*
tcp, udp x x 0 Invalid
tcp, udp 0 0 x Invalid
tcp, udp x 0 x Invalid
@@ -626,7 +623,7 @@ File: gawkinet.info, Node: Comparing Protocols, Prev:
Special File Fields, Up
-------------------------
This node develops a pair of programs (sender and receiver) that do
-nothing but send a timestamp from one machine to another. The sender
+nothing but send a timestamp from one machine to another. The sender
and the receiver are implemented with each of the two protocols
available and demonstrate the differences between them.
@@ -638,10 +635,10 @@ available and demonstrate the differences between them.
File: gawkinet.info, Node: File /inet/tcp, Next: File /inet/udp, Prev:
Comparing Protocols, Up: Comparing Protocols
-2.1.2.1 `/inet/tcp'
+2.1.2.1 '/inet/tcp'
...................
-Once again, always use TCP. (Use UDP when low overhead is a necessity,
+Once again, always use TCP. (Use UDP when low overhead is a necessity,
and use RAW for network experimentation.) The first example is the
sender program:
@@ -661,21 +658,21 @@ sender program:
}
TCP guarantees that the bytes arrive at the receiving end in exactly
-the same order that they were sent. No byte is lost (except for broken
-connections), doubled, or out of order. Some overhead is necessary to
+the same order that they were sent. No byte is lost (except for broken
+connections), doubled, or out of order. Some overhead is necessary to
accomplish this, but this is the price to pay for a reliable service.
-It does matter which side starts first. The sender/server has to be
+It does matter which side starts first. The sender/server has to be
started first, and it waits for the receiver to read a line.
File: gawkinet.info, Node: File /inet/udp, Prev: File /inet/tcp, Up:
Comparing Protocols
-2.1.2.2 `/inet/udp'
+2.1.2.2 '/inet/udp'
...................
The server and client programs that use UDP are almost identical to
-their TCP counterparts; only the PROTOCOL has changed. As before, it
-does matter which side starts first. The receiving side blocks and
+their TCP counterparts; only the PROTOCOL has changed. As before, it
+does matter which side starts first. The receiving side blocks and
waits for the sender. In this case, the receiver/client has to be
started first:
@@ -695,10 +692,11 @@ started first:
}
UDP cannot guarantee that the datagrams at the receiving end will
-arrive in exactly the same order they were sent. Some datagrams could be
-lost, some doubled, and some out of order. But no overhead is necessary
-to accomplish this. This unreliable behavior is good enough for tasks
-such as data acquisition, logging, and even stateless services like NFS.
+arrive in exactly the same order they were sent. Some datagrams could
+be lost, some doubled, and some out of order. But no overhead is
+necessary to accomplish this. This unreliable behavior is good enough
+for tasks such as data acquisition, logging, and even stateless services
+like NFS.
File: gawkinet.info, Node: TCP Connecting, Next: Troubleshooting, Prev:
Gawk Special Files, Up: Using Networking
@@ -706,10 +704,10 @@ File: gawkinet.info, Node: TCP Connecting, Next:
Troubleshooting, Prev: Gawk
2.2 Establishing a TCP Connection
=================================
-Let's observe a network connection at work. Type in the following
-program and watch the output. Within a second, it connects via TCP
-(`/inet/tcp') to the machine it is running on (`localhost') and asks
-the service `daytime' on the machine what time it is:
+Let's observe a network connection at work. Type in the following
+program and watch the output. Within a second, it connects via TCP
+('/inet/tcp') to the machine it is running on ('localhost') and asks the
+service 'daytime' on the machine what time it is:
BEGIN {
"/inet/tcp/0/localhost/daytime" |& getline
@@ -717,39 +715,39 @@ the service `daytime' on the machine what time it is:
close("/inet/tcp/0/localhost/daytime")
}
- Even experienced `awk' users will find the second line strange in two
+ Even experienced 'awk' users will find the second line strange in two
respects:
* A special file is used as a shell command that pipes its output
- into `getline'. One would rather expect to see the special file
- being read like any other file (`getline <
+ into 'getline'. One would rather expect to see the special file
+ being read like any other file ('getline <
"/inet/tcp/0/localhost/daytime")'.
- * The operator `|&' has not been part of any `awk' implementation
- (until now). It is actually the only extension of the `awk'
- language needed (apart from the special files) to introduce
- network access.
+ * The operator '|&' has not been part of any 'awk' implementation
+ (until now). It is actually the only extension of the 'awk'
+ language needed (apart from the special files) to introduce network
+ access.
- The `|&' operator was introduced in `gawk' 3.1 in order to overcome
-the crucial restriction that access to files and pipes in `awk' is
-always unidirectional. It was formerly impossible to use both access
-modes on the same file or pipe. Instead of changing the whole concept
-of file access, the `|&' operator behaves exactly like the usual pipe
+ The '|&' operator was introduced in 'gawk' 3.1 in order to overcome
+the crucial restriction that access to files and pipes in 'awk' is
+always unidirectional. It was formerly impossible to use both access
+modes on the same file or pipe. Instead of changing the whole concept
+of file access, the '|&' operator behaves exactly like the usual pipe
operator except for two additions:
- * Normal shell commands connected to their `gawk' program with a `|&'
- pipe can be accessed bidirectionally. The `|&' turns out to be a
- quite general, useful, and natural extension of `awk'.
+ * Normal shell commands connected to their 'gawk' program with a '|&'
+ pipe can be accessed bidirectionally. The '|&' turns out to be a
+ quite general, useful, and natural extension of 'awk'.
* Pipes that consist of a special file name for network connections
- are not executed as shell commands. Instead, they can be read and
+ are not executed as shell commands. Instead, they can be read and
written to, just like a full-duplex network connection.
- In the earlier example, the `|&' operator tells `getline' to read a
-line from the special file `/inet/tcp/0/localhost/daytime'. We could
-also have printed a line into the special file. But instead we just
+ In the earlier example, the '|&' operator tells 'getline' to read a
+line from the special file '/inet/tcp/0/localhost/daytime'. We could
+also have printed a line into the special file. But instead we just
read a line with the time, printed it, and closed the connection.
-(While we could just let `gawk' close the connection by finishing the
+(While we could just let 'gawk' close the connection by finishing the
program, in this Info file we are pedantic and always explicitly close
the connections.)
@@ -760,23 +758,23 @@ File: gawkinet.info, Node: Troubleshooting, Next:
Interacting, Prev: TCP Conn
=======================================
It may well be that for some reason the program shown in the previous
-example does not run on your machine. When looking at possible reasons
+example does not run on your machine. When looking at possible reasons
for this, you will learn much about typical problems that arise in
-network programming. First of all, your implementation of `gawk' may
-not support network access because it is a pre-3.1 version or you do
-not have a network interface in your machine. Perhaps your machine
-uses some other protocol, such as DECnet or Novell's IPX. For the rest
-of this major node, we will assume you work on a Unix machine that
-supports TCP/IP. If the previous example program does not run on your
-machine, it may help to replace the name `localhost' with the name of
-your machine or its IP address. If it does, you could replace
-`localhost' with the name of another machine in your vicinity--this
-way, the program connects to another machine. Now you should see the
-date and time being printed by the program, otherwise your machine may
-not support the `daytime' service. Try changing the service to
-`chargen' or `ftp'. This way, the program connects to other services
-that should give you some response. If you are curious, you should have
-a look at your `/etc/services' file. It could look like this:
+network programming. First of all, your implementation of 'gawk' may
+not support network access because it is a pre-3.1 version or you do not
+have a network interface in your machine. Perhaps your machine uses
+some other protocol, such as DECnet or Novell's IPX. For the rest of
+this major node, we will assume you work on a Unix machine that supports
+TCP/IP. If the previous example program does not run on your machine, it
+may help to replace the name 'localhost' with the name of your machine
+or its IP address. If it does, you could replace 'localhost' with the
+name of another machine in your vicinity--this way, the program connects
+to another machine. Now you should see the date and time being printed
+by the program, otherwise your machine may not support the 'daytime'
+service. Try changing the service to 'chargen' or 'ftp'. This way, the
+program connects to other services that should give you some response.
+If you are curious, you should have a look at your '/etc/services' file.
+It could look like this:
# /etc/services:
#
@@ -808,26 +806,26 @@ a look at your `/etc/services' file. It could look like
this:
...
Here, you find a list of services that traditional Unix machines
-usually support. If your GNU/Linux machine does not do so, it may be
-that these services are switched off in some startup script. Systems
+usually support. If your GNU/Linux machine does not do so, it may be
+that these services are switched off in some startup script. Systems
running some flavor of Microsoft Windows usually do _not_ support these
-services. Nevertheless, it _is_ possible to do networking with `gawk'
-on Microsoft Windows.(1) The first column of the file gives the name of
+services. Nevertheless, it _is_ possible to do networking with 'gawk'
+on Microsoft Windows.(1) The first column of the file gives the name of
the service, and the second column gives a unique number and the
protocol that one can use to connect to this service. The rest of the
-line is treated as a comment. You see that some services (`echo')
+line is treated as a comment. You see that some services ('echo')
support TCP as well as UDP.
---------- Footnotes ----------
(1) Microsoft preferred to ignore the TCP/IP family of protocols
-until 1995. Then came the rise of the Netscape browser as a landmark
-"killer application." Microsoft added TCP/IP support and their own
-browser to Microsoft Windows 95 at the last minute. They even
+until 1995. Then came the rise of the Netscape browser as a landmark
+"killer application." Microsoft added TCP/IP support and their own
+browser to Microsoft Windows 95 at the last minute. They even
back-ported their TCP/IP implementation to Microsoft Windows for
Workgroups 3.11, but it was a rather rudimentary and half-hearted
-implementation. Nevertheless, the equivalent of `/etc/services' resides
-under `C:\WINNT\system32\drivers\etc\services' on Microsoft Windows 2000
+implementation. Nevertheless, the equivalent of '/etc/services' resides
+under 'C:\WINNT\system32\drivers\etc\services' on Microsoft Windows 2000
and Microsoft Windows XP.
@@ -837,10 +835,10 @@ File: gawkinet.info, Node: Interacting, Next: Setting
Up, Prev: Troubleshooti
======================================
The next program makes use of the possibility to really interact with a
-network service by printing something into the special file. It asks the
-so-called `finger' service if a user of the machine is logged in. When
-testing this program, try to change `localhost' to some other machine
-name in your local network:
+network service by printing something into the special file. It asks
+the so-called 'finger' service if a user of the machine is logged in.
+When testing this program, try to change 'localhost' to some other
+machine name in your local network:
BEGIN {
NetService = "/inet/tcp/0/localhost/finger"
@@ -851,39 +849,39 @@ name in your local network:
}
After telling the service on the machine which user to look for, the
-program repeatedly reads lines that come as a reply. When no more lines
+program repeatedly reads lines that come as a reply. When no more lines
are coming (because the service has closed the connection), the program
-also closes the connection. Try replacing `"NAME"' with your login name
+also closes the connection. Try replacing '"NAME"' with your login name
(or the name of someone else logged in). For a list of all users
-currently logged in, replace NAME with an empty string (`""').
+currently logged in, replace NAME with an empty string ('""').
- The final `close' command could be safely deleted from the above
+ The final 'close' command could be safely deleted from the above
script, because the operating system closes any open connection by
-default when a script reaches the end of execution. In order to avoid
+default when a script reaches the end of execution. In order to avoid
portability problems, it is best to always close connections explicitly.
With the Linux kernel, for example, proper closing results in flushing
-of buffers. Letting the close happen by default may result in
+of buffers. Letting the close happen by default may result in
discarding buffers.
- When looking at `/etc/services' you may have noticed that the
-`daytime' service is also available with `udp'. In the earlier example,
-change `tcp' to `udp', and change `finger' to `daytime'. After
-starting the modified program, you see the expected day and time
-message. The program then hangs, because it waits for more lines
-coming from the service. However, they never come. This behavior is a
-consequence of the differences between TCP and UDP. When using UDP,
-neither party is automatically informed about the other closing the
-connection. Continuing to experiment this way reveals many other subtle
-differences between TCP and UDP. To avoid such trouble, one should
-always remember the advice Douglas E. Comer and David Stevens give in
-Volume III of their series `Internetworking With TCP' (page 14):
+ When looking at '/etc/services' you may have noticed that the
+'daytime' service is also available with 'udp'. In the earlier example,
+change 'tcp' to 'udp', and change 'finger' to 'daytime'. After starting
+the modified program, you see the expected day and time message. The
+program then hangs, because it waits for more lines coming from the
+service. However, they never come. This behavior is a consequence of
+the differences between TCP and UDP. When using UDP, neither party is
+automatically informed about the other closing the connection.
+Continuing to experiment this way reveals many other subtle differences
+between TCP and UDP. To avoid such trouble, one should always remember
+the advice Douglas E. Comer and David Stevens give in Volume III of
+their series 'Internetworking With TCP' (page 14):
When designing client-server applications, beginners are strongly
advised to use TCP because it provides reliable,
- connection-oriented communication. Programs only use UDP if the
+ connection-oriented communication. Programs only use UDP if the
application protocol handles reliability, the application requires
- hardware broadcast or multicast, or the application cannot
- tolerate virtual circuit overhead.
+ hardware broadcast or multicast, or the application cannot tolerate
+ virtual circuit overhead.
File: gawkinet.info, Node: Setting Up, Next: Email, Prev: Interacting, Up:
Using Networking
@@ -892,17 +890,17 @@ File: gawkinet.info, Node: Setting Up, Next: Email,
Prev: Interacting, Up: U
========================
The preceding programs behaved as clients that connect to a server
-somewhere on the Internet and request a particular service. Now we set
-up such a service to mimic the behavior of the `daytime' service. Such
-a server does not know in advance who is going to connect to it over
-the network. Therefore, we cannot insert a name for the host to connect
-to in our special file name.
-
- Start the following program in one window. Notice that the service
-does not have the name `daytime', but the number `8888'. From looking
-at `/etc/services', you know that names like `daytime' are just
+somewhere on the Internet and request a particular service. Now we set
+up such a service to mimic the behavior of the 'daytime' service. Such
+a server does not know in advance who is going to connect to it over the
+network. Therefore, we cannot insert a name for the host to connect to
+in our special file name.
+
+ Start the following program in one window. Notice that the service
+does not have the name 'daytime', but the number '8888'. From looking
+at '/etc/services', you know that names like 'daytime' are just
mnemonics for predetermined 16-bit integers. Only the system
-administrator (`root') could enter our new service into `/etc/services'
+administrator ('root') could enter our new service into '/etc/services'
with an appropriate name. Also notice that the service name has to be
entered into a different field of the special file name because we are
setting up a server, not a client:
@@ -912,35 +910,35 @@ setting up a server, not a client:
close("/inet/tcp/8888/0/0")
}
- Now open another window on the same machine. Copy the client
-program given as the first example (*note Establishing a TCP
-Connection: TCP Connecting.) to a new file and edit it, changing the
-name `daytime' to `8888'. Then start the modified client. You should
-get a reply like this:
+ Now open another window on the same machine. Copy the client program
+given as the first example (*note Establishing a TCP Connection: TCP
+Connecting.) to a new file and edit it, changing the name 'daytime' to
+'8888'. Then start the modified client. You should get a reply like
+this:
Sat Sep 27 19:08:16 CEST 1997
Both programs explicitly close the connection.
- Now we will intentionally make a mistake to see what happens when
-the name `8888' (the so-called port) is already used by another service.
-Start the server program in both windows. The first one works, but the
-second one complains that it could not open the connection. Each port
+ Now we will intentionally make a mistake to see what happens when the
+name '8888' (the so-called port) is already used by another service.
+Start the server program in both windows. The first one works, but the
+second one complains that it could not open the connection. Each port
on a single machine can only be used by one server program at a time.
-Now terminate the server program and change the name `8888' to `echo'.
+Now terminate the server program and change the name '8888' to 'echo'.
After restarting it, the server program does not run any more, and you
-know why: there is already an `echo' service running on your machine.
-But even if this isn't true, you would not get your own `echo' server
+know why: there is already an 'echo' service running on your machine.
+But even if this isn't true, you would not get your own 'echo' server
running on a Unix machine, because the ports with numbers smaller than
-1024 (`echo' is at port 7) are reserved for `root'. On machines
-running some flavor of Microsoft Windows, there is no restriction that
-reserves ports 1 to 1024 for a privileged user; hence, you can start an
-`echo' server there.
+1024 ('echo' is at port 7) are reserved for 'root'. On machines running
+some flavor of Microsoft Windows, there is no restriction that reserves
+ports 1 to 1024 for a privileged user; hence, you can start an 'echo'
+server there.
Turning this short server program into something really useful is
simple. Imagine a server that first reads a file name from the client
through the network connection, then does something with the file and
-sends a result back to the client. The server-side processing could be:
+sends a result back to the client. The server-side processing could be:
BEGIN {
NetService = "/inet/tcp/8888/0/0"
@@ -951,13 +949,13 @@ sends a result back to the client. The server-side
processing could be:
close(NetService)
}
-and we would have a remote copying facility. Such a server reads the
+and we would have a remote copying facility. Such a server reads the
name of a file from any client that connects to it and transmits the
-contents of the named file across the net. The server-side processing
+contents of the named file across the net. The server-side processing
could also be the execution of a command that is transmitted across the
-network. From this example, you can see how simple it is to open up a
-security hole on your machine. If you allow clients to connect to your
-machine and execute arbitrary commands, anyone would be free to do `rm
+network. From this example, you can see how simple it is to open up a
+security hole on your machine. If you allow clients to connect to your
+machine and execute arbitrary commands, anyone would be free to do 'rm
-rf *'.
@@ -967,16 +965,16 @@ File: gawkinet.info, Node: Email, Next: Web page,
Prev: Setting Up, Up: Usin
=================
The distribution of email is usually done by dedicated email servers
-that communicate with your machine using special protocols. To receive
-email, we will use the Post Office Protocol (POP). Sending can be done
+that communicate with your machine using special protocols. To receive
+email, we will use the Post Office Protocol (POP). Sending can be done
with the much older Simple Mail Transfer Protocol (SMTP).
When you type in the following program, replace the EMAILHOST by the
-name of your local email server. Ask your administrator if the server
+name of your local email server. Ask your administrator if the server
has a POP service, and then use its name or number in the program below.
Now the program is ready to connect to your email server, but it will
not succeed in retrieving your mail because it does not yet know your
-login name or password. Replace them in the program and it shows you
+login name or password. Replace them in the program and it shows you
the first email the server has in store:
BEGIN {
@@ -996,16 +994,16 @@ the first email the server has in store:
close(POPService)
}
- The record separators `RS' and `ORS' are redefined because the
-protocol (POP) requires CR-LF to separate lines. After identifying
-yourself to the email service, the command `retr 1' instructs the
-service to send the first of all your email messages in line. If the
-service replies with something other than `+OK', the program exits;
-maybe there is no email. Otherwise, the program first announces that it
-intends to finish reading email, and then redefines `RS' in order to
-read the entire email as multiline input in one record. From the POP
+ The record separators 'RS' and 'ORS' are redefined because the
+protocol (POP) requires CR-LF to separate lines. After identifying
+yourself to the email service, the command 'retr 1' instructs the
+service to send the first of all your email messages in line. If the
+service replies with something other than '+OK', the program exits;
+maybe there is no email. Otherwise, the program first announces that it
+intends to finish reading email, and then redefines 'RS' in order to
+read the entire email as multiline input in one record. From the POP
RFC, we know that the body of the email always ends with a single line
-containing a single dot. The program looks for this using `RS =
+containing a single dot. The program looks for this using 'RS =
"\r\n\\.\r\n"'. When it finds this sequence in the mail message, it
quits. You can invoke this program as often as you like; it does not
delete the message it reads, but instead leaves it on the server.
@@ -1016,20 +1014,19 @@ File: gawkinet.info, Node: Web page, Next: Primitive
Service, Prev: Email, U
2.7 Reading a Web Page
======================
-Retrieving a web page from a web server is as simple as retrieving
-email from an email server. We only have to use a similar, but not
-identical, protocol and a different port. The name of the protocol is
-HyperText Transfer Protocol (HTTP) and the port number is usually 80.
-As in the preceding node, ask your administrator about the name of your
-local web server or proxy web server and its port number for HTTP
-requests.
+Retrieving a web page from a web server is as simple as retrieving email
+from an email server. We only have to use a similar, but not identical,
+protocol and a different port. The name of the protocol is HyperText
+Transfer Protocol (HTTP) and the port number is usually 80. As in the
+preceding node, ask your administrator about the name of your local web
+server or proxy web server and its port number for HTTP requests.
The following program employs a rather crude approach toward
-retrieving a web page. It uses the prehistoric syntax of HTTP 0.9,
-which almost all web servers still support. The most noticeable thing
+retrieving a web page. It uses the prehistoric syntax of HTTP 0.9,
+which almost all web servers still support. The most noticeable thing
about it is that the program directs the request to the local proxy
server whose name you insert in the special file name (which in turn
-calls `www.yahoo.com'):
+calls 'www.yahoo.com'):
BEGIN {
RS = ORS = "\r\n"
@@ -1040,29 +1037,29 @@ calls `www.yahoo.com'):
close(HttpService)
}
- Again, lines are separated by a redefined `RS' and `ORS'. The `GET'
-request that we send to the server is the only kind of HTTP request
-that existed when the web was created in the early 1990s. HTTP calls
-this `GET' request a "method," which tells the service to transmit a
-web page (here the home page of the Yahoo! search engine). Version 1.0
-added the request methods `HEAD' and `POST'. The current version of
-HTTP is 1.1,(1) and knows the additional request methods `OPTIONS',
-`PUT', `DELETE', and `TRACE'. You can fill in any valid web address,
-and the program prints the HTML code of that page to your screen.
+ Again, lines are separated by a redefined 'RS' and 'ORS'. The 'GET'
+request that we send to the server is the only kind of HTTP request that
+existed when the web was created in the early 1990s. HTTP calls this
+'GET' request a "method," which tells the service to transmit a web page
+(here the home page of the Yahoo! search engine). Version 1.0 added
+the request methods 'HEAD' and 'POST'. The current version of HTTP is
+1.1,(1) and knows the additional request methods 'OPTIONS', 'PUT',
+'DELETE', and 'TRACE'. You can fill in any valid web address, and the
+program prints the HTML code of that page to your screen.
Notice the similarity between the responses of the POP and HTTP
-services. First, you get a header that is terminated by an empty line,
-and then you get the body of the page in HTML. The lines of the
-headers also have the same form as in POP. There is the name of a
-parameter, then a colon, and finally the value of that parameter.
+services. First, you get a header that is terminated by an empty line,
+and then you get the body of the page in HTML. The lines of the headers
+also have the same form as in POP. There is the name of a parameter,
+then a colon, and finally the value of that parameter.
- Images (`.png' or `.gif' files) can also be retrieved this way, but
-then you get binary data that should be redirected into a file. Another
+ Images ('.png' or '.gif' files) can also be retrieved this way, but
+then you get binary data that should be redirected into a file. Another
application is calling a CGI (Common Gateway Interface) script on some
-server. CGI scripts are used when the contents of a web page are not
+server. CGI scripts are used when the contents of a web page are not
constant, but generated instantly at the moment you send a request for
-the page. For example, to get a detailed report about the current
-quotes of Motorola stock shares, call a CGI script at Yahoo! with the
+the page. For example, to get a detailed report about the current
+quotes of Motorola stock shares, call a CGI script at Yahoo! with the
following:
get = "GET http://quote.yahoo.com/q?s=MOT&d=t";
@@ -1073,7 +1070,7 @@ following:
---------- Footnotes ----------
(1) Version 1.0 of HTTP was defined in RFC 1945. HTTP 1.1 was
-initially specified in RFC 2068. In June 1999, RFC 2068 was made
+initially specified in RFC 2068. In June 1999, RFC 2068 was made
obsolete by RFC 2616, an update without any substantial changes.
@@ -1083,31 +1080,31 @@ File: gawkinet.info, Node: Primitive Service, Next:
Interacting Service, Prev
===========================
Now we know enough about HTTP to set up a primitive web service that
-just says `"Hello, world"' when someone connects to it with a browser.
-Compared to the situation in the preceding node, our program changes
-the role. It tries to behave just like the server we have observed.
-Since we are setting up a server here, we have to insert the port
-number in the `localport' field of the special file name. The other two
-fields (HOSTNAME and REMOTEPORT) have to contain a `0' because we do
-not know in advance which host will connect to our service.
+just says '"Hello, world"' when someone connects to it with a browser.
+Compared to the situation in the preceding node, our program changes the
+role. It tries to behave just like the server we have observed. Since
+we are setting up a server here, we have to insert the port number in
+the 'localport' field of the special file name. The other two fields
+(HOSTNAME and REMOTEPORT) have to contain a '0' because we do not know
+in advance which host will connect to our service.
In the early 1990s, all a server had to do was send an HTML document
-and close the connection. Here, we adhere to the modern syntax of HTTP.
+and close the connection. Here, we adhere to the modern syntax of HTTP.
The steps are as follows:
1. Send a status line telling the web browser that everything is okay.
2. Send a line to tell the browser how many bytes follow in the body
- of the message. This was not necessary earlier because both
+ of the message. This was not necessary earlier because both
parties knew that the document ended when the connection closed.
- Nowadays it is possible to stay connected after the transmission
- of one web page. This is to avoid the network traffic necessary
- for repeatedly establishing TCP connections for requesting several
- images. Thus, there is the need to tell the receiving party how
- many bytes will be sent. The header is terminated as usual with an
+ Nowadays it is possible to stay connected after the transmission of
+ one web page. This is to avoid the network traffic necessary for
+ repeatedly establishing TCP connections for requesting several
+ images. Thus, there is the need to tell the receiving party how
+ many bytes will be sent. The header is terminated as usual with an
empty line.
- 3. Send the `"Hello, world"' body in HTML. The useless `while' loop
+ 3. Send the '"Hello, world"' body in HTML. The useless 'while' loop
swallows the request of the browser. We could actually omit the
loop, and on most machines the program would still work. First,
start the following program:
@@ -1128,8 +1125,8 @@ The steps are as follows:
}
Now, on the same machine, start your favorite browser and let it
-point to `http://localhost:8080' (the browser needs to know on which
-port our server is listening for requests). If this does not work, the
+point to <http://localhost:8080> (the browser needs to know on which
+port our server is listening for requests). If this does not work, the
browser probably tries to connect to a proxy server that does not know
your machine. If so, change the browser's configuration so that the
browser does not try to use a proxy to connect to your machine.
@@ -1149,14 +1146,14 @@ Applications and Techniques::.
* CGI Lib:: A simple CGI library.
Setting up a web service that allows user interaction is more
-difficult and shows us the limits of network access in `gawk'. In this
-node, we develop a main program (a `BEGIN' pattern and its action)
-that will become the core of event-driven execution controlled by a
-graphical user interface (GUI). Each HTTP event that the user triggers
-by some action within the browser is received in this central
-procedure. Parameters and menu choices are extracted from this request,
-and an appropriate measure is taken according to the user's choice.
-For example:
+difficult and shows us the limits of network access in 'gawk'. In this
+node, we develop a main program (a 'BEGIN' pattern and its action) that
+will become the core of event-driven execution controlled by a graphical
+user interface (GUI). Each HTTP event that the user triggers by some
+action within the browser is received in this central procedure.
+Parameters and menu choices are extracted from this request, and an
+appropriate measure is taken according to the user's choice. For
+example:
BEGIN {
if (MyHost == "") {
@@ -1205,17 +1202,17 @@ For example:
This web server presents menu choices in the form of HTML links.
Therefore, it has to tell the browser the name of the host it is
-residing on. When starting the server, the user may supply the name of
-the host from the command line with `gawk -v MyHost="Rumpelstilzchen"'.
+residing on. When starting the server, the user may supply the name of
+the host from the command line with 'gawk -v MyHost="Rumpelstilzchen"'.
If the user does not do this, the server looks up the name of the host
-it is running on for later use as a web address in HTML documents. The
-same applies to the port number. These values are inserted later into
+it is running on for later use as a web address in HTML documents. The
+same applies to the port number. These values are inserted later into
the HTML content of the web pages to refer to the home system.
Each server that is built around this core has to initialize some
application-dependent variables (such as the default home page) in a
-procedure `SetUpServer', which is called immediately before entering the
-infinite loop of the server. For now, we will write an instance that
+procedure 'SetUpServer', which is called immediately before entering the
+infinite loop of the server. For now, we will write an instance that
initiates a trivial interaction. With this home page, the client user
can click on two possible choices, and receive the current date either
in human-readable format or in seconds since 1970:
@@ -1233,33 +1230,33 @@ in human-readable format or in seconds since 1970:
On the first run through the main loop, the default line terminators
are set and the default home page is copied to the actual home page.
-Since this is the first run, `GETARG["Method"]' is not initialized yet,
-hence the case selection over the method does nothing. Now that the
-home page is initialized, the server can start communicating to a
-client browser.
+Since this is the first run, 'GETARG["Method"]' is not initialized yet,
+hence the case selection over the method does nothing. Now that the
+home page is initialized, the server can start communicating to a client
+browser.
It does so by printing the HTTP header into the network connection
-(`print ... |& HttpService'). This command blocks execution of the
-server script until a client connects. If this server script is
+('print ... |& HttpService'). This command blocks execution of the
+server script until a client connects. If this server script is
compared with the primitive one we wrote before, you will notice two
-additional lines in the header. The first instructs the browser to
-close the connection after each request. The second tells the browser
+additional lines in the header. The first instructs the browser to
+close the connection after each request. The second tells the browser
that it should never try to _remember_ earlier requests that had
-identical web addresses (no caching). Otherwise, it could happen that
+identical web addresses (no caching). Otherwise, it could happen that
the browser retrieves the time of day in the previous example just once,
and later it takes the web page from the cache, always displaying the
same time of day although time advances each second.
Having supplied the initial home page to the browser with a valid
-document stored in the parameter `Prompt', it closes the connection and
+document stored in the parameter 'Prompt', it closes the connection and
waits for the next request. When the request comes, a log line is
-printed that allows us to see which request the server receives. The
-final step in the loop is to call the function `CGI_setup', which reads
+printed that allows us to see which request the server receives. The
+final step in the loop is to call the function 'CGI_setup', which reads
all the lines of the request (coming from the browser), processes them,
-and stores the transmitted parameters in the array `PARAM'. The complete
-text of these application-independent functions can be found in *note A
-Simple CGI Library: CGI Lib. For now, we use a simplified version of
-`CGI_setup':
+and stores the transmitted parameters in the array 'PARAM'. The
+complete text of these application-independent functions can be found in
+*note A Simple CGI Library: CGI Lib. For now, we use a simplified
+version of 'CGI_setup':
function CGI_setup( method, uri, version, i) {
delete GETARG; delete MENU; delete PARAM
@@ -1282,30 +1279,30 @@ Simple CGI Library: CGI Lib. For now, we use a
simplified version of
}
At first, the function clears all variables used for global storage
-of request parameters. The rest of the function serves the purpose of
+of request parameters. The rest of the function serves the purpose of
filling the global parameters with the extracted new values. To
accomplish this, the name of the requested resource is split into parts
-and stored for later evaluation. If the request contains a `?', then
+and stored for later evaluation. If the request contains a '?', then
the request has CGI variables seamlessly appended to the web address.
-Everything in front of the `?' is split up into menu items, and
-everything behind the `?' is a list of `VARIABLE=VALUE' pairs
-(separated by `&') that also need splitting. This way, CGI variables are
-isolated and stored. This procedure lacks recognition of special
-characters that are transmitted in coded form(1). Here, any optional
-request header and body parts are ignored. We do not need header
-parameters and the request body. However, when refining our approach or
-working with the `POST' and `PUT' methods, reading the header and body
-becomes inevitable. Header parameters should then be stored in a global
-array as well as the body.
+Everything in front of the '?' is split up into menu items, and
+everything behind the '?' is a list of 'VARIABLE=VALUE' pairs (separated
+by '&') that also need splitting. This way, CGI variables are isolated
+and stored. This procedure lacks recognition of special characters that
+are transmitted in coded form(1). Here, any optional request header and
+body parts are ignored. We do not need header parameters and the
+request body. However, when refining our approach or working with the
+'POST' and 'PUT' methods, reading the header and body becomes
+inevitable. Header parameters should then be stored in a global array
+as well as the body.
On each subsequent run through the main loop, one request from a
browser is received, evaluated, and answered according to the user's
-choice. This can be done by letting the value of the HTTP method guide
-the main loop into execution of the procedure `HandleGET', which
-evaluates the user's choice. In this case, we have only one
+choice. This can be done by letting the value of the HTTP method guide
+the main loop into execution of the procedure 'HandleGET', which
+evaluates the user's choice. In this case, we have only one
hierarchical level of menus, but in the general case, menus are nested.
-The menu choices at each level are separated by `/', just as in file
-names. Notice how simple it is to construct menus of arbitrary depth:
+The menu choices at each level are separated by '/', just as in file
+names. Notice how simple it is to construct menus of arbitrary depth:
function HandleGET() {
if ( MENU[2] == "human") {
@@ -1316,19 +1313,19 @@ names. Notice how simple it is to construct menus of
arbitrary depth:
}
The disadvantage of this approach is that our server is slow and can
-handle only one request at a time. Its main advantage, however, is that
-the server consists of just one `gawk' program. No need for installing
-an `httpd', and no need for static separate HTML files, CGI scripts, or
-`root' privileges. This is rapid prototyping. This program can be
+handle only one request at a time. Its main advantage, however, is that
+the server consists of just one 'gawk' program. No need for installing
+an 'httpd', and no need for static separate HTML files, CGI scripts, or
+'root' privileges. This is rapid prototyping. This program can be
started on the same host that runs your browser. Then let your browser
-point to `http://localhost:8080'.
+point to <http://localhost:8080>.
It is also possible to include images into the HTML pages. Most
-browsers support the not very well-known `.xbm' format, which may
-contain only monochrome pictures but is an ASCII format. Binary images
-are possible but not so easy to handle. Another way of including images
+browsers support the not very well-known '.xbm' format, which may
+contain only monochrome pictures but is an ASCII format. Binary images
+are possible but not so easy to handle. Another way of including images
is to generate them with a tool such as GNUPlot, by calling the tool
-with the `system' function or through a pipe.
+with the 'system' function or through a pipe.
---------- Footnotes ----------
@@ -1343,25 +1340,25 @@ File: gawkinet.info, Node: CGI Lib, Prev: Interacting
Service, Up: Interactin
HTTP is like being married: you have to be able to handle whatever
you're given, while being very careful what you send back.
Phil Smith III,
- `http://www.netfunny.com/rhf/jokes/99/Mar/http.html'
+ <http://www.netfunny.com/rhf/jokes/99/Mar/http.html>
In *note A Web Service with Interaction: Interacting Service, we saw
-the function `CGI_setup' as part of the web server "core logic"
-framework. The code presented there handles almost everything necessary
+the function 'CGI_setup' as part of the web server "core logic"
+framework. The code presented there handles almost everything necessary
for CGI requests. One thing it doesn't do is handle encoded characters
-in the requests. For example, an `&' is encoded as a percent sign
-followed by the hexadecimal value: `%26'. These encoded values should
-be decoded. Following is a simple library to perform these tasks.
-This code is used for all web server examples used throughout the rest
-of this Info file. If you want to use it for your own web server,
-store the source code into a file named `inetlib.awk'. Then you can
-include these functions into your code by placing the following
-statement into your program (on the first line of your script):
+in the requests. For example, an '&' is encoded as a percent sign
+followed by the hexadecimal value: '%26'. These encoded values should
+be decoded. Following is a simple library to perform these tasks. This
+code is used for all web server examples used throughout the rest of
+this Info file. If you want to use it for your own web server, store
+the source code into a file named 'inetlib.awk'. Then you can include
+these functions into your code by placing the following statement into
+your program (on the first line of your script):
@include inetlib.awk
But beware, this mechanism is only possible if you invoke your web
-server script with `igawk' instead of the usual `awk' or `gawk'. Here
+server script with 'igawk' instead of the usual 'awk' or 'gawk'. Here
is the code:
# CGI Library and core of a web server
@@ -1446,11 +1443,11 @@ is the code:
MENU[i] = _CGI_decode(MENU[i])
}
- This isolates details in a single function, `CGI_setup'. Decoding
-of encoded characters is pushed off to a helper function,
-`_CGI_decode'. The use of the leading underscore (`_') in the function
-name is intended to indicate that it is an "internal" function,
-although there is nothing to enforce this:
+ This isolates details in a single function, 'CGI_setup'. Decoding of
+encoded characters is pushed off to a helper function, '_CGI_decode'.
+The use of the leading underscore ('_') in the function name is intended
+to indicate that it is an "internal" function, although there is nothing
+to enforce this:
function _CGI_decode(str, hexdigs, i, pre, code1, code2,
val, result)
@@ -1482,10 +1479,10 @@ although there is nothing to enforce this:
This works by splitting the string apart around an encoded character.
The two digits are converted to lowercase characters and looked up in a
-string of hex digits. Note that `0' is not in the string on purpose;
-`index' returns zero when it's not found, automatically giving the
+string of hex digits. Note that '0' is not in the string on purpose;
+'index' returns zero when it's not found, automatically giving the
correct value! Once the hexadecimal value is converted from characters
-in a string into a numerical value, `sprintf' converts the value back
+in a string into a numerical value, 'sprintf' converts the value back
into a real character. The following is a simple test harness for the
above functions:
@@ -1530,14 +1527,14 @@ File: gawkinet.info, Node: Simple Server, Next:
Caveats, Prev: Interacting Se
In the preceding node, we built the core logic for event-driven GUIs.
In this node, we finally extend the core to a real application. No one
-would actually write a commercial web server in `gawk', but it is
+would actually write a commercial web server in 'gawk', but it is
instructive to see that it is feasible in principle.
The application is ELIZA, the famous program by Joseph Weizenbaum
that mimics the behavior of a professional psychotherapist when talking
-to you. Weizenbaum would certainly object to this description, but
-this is part of the legend around ELIZA. Take the site-independent
-core logic and append the following code:
+to you. Weizenbaum would certainly object to this description, but this
+is part of the legend around ELIZA. Take the site-independent core logic
+and append the following code:
function SetUpServer() {
SetUpEliza()
@@ -1561,22 +1558,22 @@ core logic and append the following code:
TopFooter = "</BODY></HTML>"
}
- `SetUpServer' is similar to the previous example, except for calling
-another function, `SetUpEliza'. This approach can be used to implement
+ 'SetUpServer' is similar to the previous example, except for calling
+another function, 'SetUpEliza'. This approach can be used to implement
other kinds of servers. The only changes needed to do so are hidden in
-the functions `SetUpServer' and `HandleGET'. Perhaps it might be
-necessary to implement other HTTP methods. The `igawk' program that
-comes with `gawk' may be useful for this process.
+the functions 'SetUpServer' and 'HandleGET'. Perhaps it might be
+necessary to implement other HTTP methods. The 'igawk' program that
+comes with 'gawk' may be useful for this process.
When extending this example to a complete application, the first
-thing to do is to implement the function `SetUpServer' to initialize
-the HTML pages and some variables. These initializations determine the
-way your HTML pages look (colors, titles, menu items, etc.).
+thing to do is to implement the function 'SetUpServer' to initialize the
+HTML pages and some variables. These initializations determine the way
+your HTML pages look (colors, titles, menu items, etc.).
- The function `HandleGET' is a nested case selection that decides
+ The function 'HandleGET' is a nested case selection that decides
which page the user wants to see next. Each nesting level refers to a
menu level of the GUI. Each case implements a certain action of the
-menu. On the deepest level of case selection, the handler essentially
+menu. On the deepest level of case selection, the handler essentially
knows what the user wants and stores the answer into the variable that
holds the HTML page contents:
@@ -1613,11 +1610,11 @@ holds the HTML page contents:
Initially the user does not say anything; then ELIZA resets its money
counter and asks the user to tell what comes to mind open heartedly.
The subsequent answers are converted to uppercase characters and stored
-for later comparison. ELIZA presents the bill when being confronted with
-a sentence that contains the phrase "shut up." Otherwise, it looks for
-keywords in the sentence, conjugates the rest of the sentence, remembers
-the keyword for later use, and finally selects an answer from the set of
-possible answers:
+for later comparison. ELIZA presents the bill when being confronted
+with a sentence that contains the phrase "shut up." Otherwise, it looks
+for keywords in the sentence, conjugates the rest of the sentence,
+remembers the keyword for later use, and finally selects an answer from
+the set of possible answers:
function ElizaSays(YouSay) {
if (YouSay == "") {
@@ -1662,9 +1659,9 @@ possible answers:
return answer
}
- In the long but simple function `SetUpEliza', you can see tables for
-conjugation, keywords, and answers.(1) The associative array `k'
-contains indices into the array of answers `r'. To choose an answer,
+ In the long but simple function 'SetUpEliza', you can see tables for
+conjugation, keywords, and answers.(1) The associative array 'k'
+contains indices into the array of answers 'r'. To choose an answer,
ELIZA just picks an index randomly:
function SetUpEliza() {
@@ -1698,19 +1695,18 @@ ELIZA just picks an index randomly:
k["YOU ARE"] =\
k["YOURE"] = "6 7 8 9"
...
-
}
Some interesting remarks and details (including the original source
code of ELIZA) are found on Mark Humphrys' home page. Yahoo! also has
-a page with a collection of ELIZA-like programs. Many of them are
-written in Java, some of them disclosing the Java source code, and a
-few even explain how to modify the Java source code.
+a page with a collection of ELIZA-like programs. Many of them are
+written in Java, some of them disclosing the Java source code, and a few
+even explain how to modify the Java source code.
---------- Footnotes ----------
(1) The version shown here is abbreviated. The full version comes
-with the `gawk' distribution.
+with the 'gawk' distribution.
File: gawkinet.info, Node: Caveats, Next: Challenges, Prev: Simple Server,
Up: Using Networking
@@ -1721,7 +1717,7 @@ File: gawkinet.info, Node: Caveats, Next: Challenges,
Prev: Simple Server, U
By now it should be clear that debugging a networked application is more
complicated than debugging a single-process single-hosted application.
The behavior of a networked application sometimes looks noncausal
-because it is not reproducible in a strong sense. Whether a network
+because it is not reproducible in a strong sense. Whether a network
application works or not sometimes depends on the following:
* How crowded the underlying network is
@@ -1731,13 +1727,12 @@ application works or not sometimes depends on the
following:
* The state of the party at the other end
The most difficult problems for a beginner arise from the hidden
-states of the underlying network. After closing a TCP connection, it's
+states of the underlying network. After closing a TCP connection, it's
often necessary to wait a short while before reopening the connection.
-Even more difficult is the establishment of a connection that
-previously ended with a "broken pipe." Those connections have to "time
-out" for a minute or so before they can reopen. Check this with the
-command `netstat -a', which provides a list of still "active"
-connections.
+Even more difficult is the establishment of a connection that previously
+ended with a "broken pipe." Those connections have to "time out" for a
+minute or so before they can reopen. Check this with the command
+'netstat -a', which provides a list of still "active" connections.
File: gawkinet.info, Node: Challenges, Prev: Caveats, Up: Using Networking
@@ -1745,18 +1740,17 @@ File: gawkinet.info, Node: Challenges, Prev: Caveats,
Up: Using Networking
2.12 Where To Go From Here
==========================
-Now, you have learned enough to build your own application. You could,
+Now, you have learned enough to build your own application. You could,
for example, take part in the Loebner Contest to win $100,000. The
-Loebner Prize is the first formal instantiation of a Turing Test. Hugh
+Loebner Prize is the first formal instantiation of a Turing Test. Hugh
Loebner agreed with The Cambridge Center for Behavioral Studies to
-underwrite a contest designed to implement the Turing Test. Dr.
-Loebner pledged a Grand Prize of $100,000 for the first computer whose
-responses were indistinguishable from a human's. Each year an annual
-prize of $2000 and a bronze medal is awarded to the _most_ human
-computer. The winner of the annual contest is the best entry relative
-to other entries that year, irrespective of how good it is in an
-absolute sense. Here is an example of a conversation with the winning
-program of 1997:
+underwrite a contest designed to implement the Turing Test. Dr. Loebner
+pledged a Grand Prize of $100,000 for the first computer whose responses
+were indistinguishable from a human's. Each year an annual prize of
+$2000 and a bronze medal is awarded to the _most_ human computer. The
+winner of the annual contest is the best entry relative to other entries
+that year, irrespective of how good it is in an absolute sense. Here is
+an example of a conversation with the winning program of 1997:
(c)1997 Cambridge Center For Behavioral Studies all rights reserved
[CONVERSE]
[Intelligent Research Ltd.] Start at: [1997/04/29 08:59:40]
@@ -1799,44 +1793,44 @@ program of 1997:
PROGRAM[10:49:02]Do you think of yourself as being attractive?
This program insists on always speaking about the same story around
-Bill Clinton. You see, even a program with a rather narrow mind can
-behave so much like a human being that it can win this prize. It is
+Bill Clinton. You see, even a program with a rather narrow mind can
+behave so much like a human being that it can win this prize. It is
quite common to let these programs talk to each other via network
-connections. But during the competition itself, the program and its
-computer have to be present at the place the competition is held. We
-all would love to see a `gawk' program win in such an event. Maybe it
+connections. But during the competition itself, the program and its
+computer have to be present at the place the competition is held. We
+all would love to see a 'gawk' program win in such an event. Maybe it
is up to you to accomplish this?
Some other ideas for useful networked applications:
- * Read the file `doc/awkforai.txt' in the `gawk' distribution. It
+ * Read the file 'doc/awkforai.txt' in the 'gawk' distribution. It
was written by Ronald P. Loui (at the time, Associate Professor of
- Computer Science, at Washington University in St. Louis,
- <address@hidden>) and summarizes why he taught `gawk' to
- students of Artificial Intelligence. Here are some passages from
+ Computer Science, at Washington University in St. Louis,
+ <address@hidden>) and summarizes why he taught 'gawk' to
+ students of Artificial Intelligence. Here are some passages from
the text:
The GAWK manual can be consumed in a single lab session and
the language can be mastered by the next morning by the
average student. GAWK's automatic initialization, implicit
- coercion, I/O support and lack of pointers forgive many of
- the mistakes that young programmers are likely to make.
- Those who have seen C but not mastered it are happy to see
- that GAWK retains some of the same sensibilities while adding
- what must be regarded as spoonsful of syntactic sugar.
+ coercion, I/O support and lack of pointers forgive many of the
+ mistakes that young programmers are likely to make. Those who
+ have seen C but not mastered it are happy to see that GAWK
+ retains some of the same sensibilities while adding what must
+ be regarded as spoonsful of syntactic sugar.
...
There are further simple answers. Probably the best is the
fact that increasingly, undergraduate AI programming is
involving the Web. Oren Etzioni (University of Washington,
Seattle) has for a while been arguing that the "softbot" is
replacing the mechanical engineers' robot as the most
- glamorous AI testbed. If the artifact whose behavior needs
- to be controlled in an intelligent way is the software agent,
+ glamorous AI testbed. If the artifact whose behavior needs to
+ be controlled in an intelligent way is the software agent,
then a language that is well-suited to controlling the
software environment is the appropriate language. That would
imply a scripting language. If the robot is KAREL, then the
- right language is "turn left; turn right." If the robot is
+ right language is "turn left; turn right." If the robot is
Netscape, then the right language is something that can
- generate `netscape -remote
+ generate 'netscape -remote
'openURL(http://cs.wustl.edu/~loui)'' with elan.
...
AI programming requires high-level thinking. There have
@@ -1847,39 +1841,39 @@ is up to you to accomplish this?
Second, inference is merely the expansion of notation. No
matter whether the logic that underlies an AI program is
fuzzy, probabilistic, deontic, defeasible, or deductive, the
- logic merely defines how strings can be transformed into
- other strings. A language that provides the best support for
- string processing in the end provides the best support for
- logic, for the exploration of various logics, and for most
- forms of symbolic processing that AI might choose to call
- "reasoning" instead of "logic." The implication is that
- PROLOG, which saves the AI programmer from having to write a
- unifier, saves perhaps two dozen lines of GAWK code at the
- expense of strongly biasing the logic and representational
- expressiveness of any approach.
-
- Now that `gawk' itself can connect to the Internet, it should be
+ logic merely defines how strings can be transformed into other
+ strings. A language that provides the best support for string
+ processing in the end provides the best support for logic, for
+ the exploration of various logics, and for most forms of
+ symbolic processing that AI might choose to call "reasoning"
+ instead of "logic." The implication is that PROLOG, which
+ saves the AI programmer from having to write a unifier, saves
+ perhaps two dozen lines of GAWK code at the expense of
+ strongly biasing the logic and representational expressiveness
+ of any approach.
+
+ Now that 'gawk' itself can connect to the Internet, it should be
obvious that it is suitable for writing intelligent web agents.
- * `awk' is strong at pattern recognition and string processing. So,
+ * 'awk' is strong at pattern recognition and string processing. So,
it is well suited to the classic problem of language translation.
A first try could be a program that knows the 100 most frequent
- English words and their counterparts in German or French. The
+ English words and their counterparts in German or French. The
service could be implemented by regularly reading email with the
program above, replacing each word by its translation and sending
- the translation back via SMTP. Users would send English email to
+ the translation back via SMTP. Users would send English email to
their translation service and get back a translated email message
- in return. As soon as this works, more effort can be spent on a
+ in return. As soon as this works, more effort can be spent on a
real translation program.
- * Another dialogue-oriented application (on the verge of ridicule)
- is the email "support service." Troubled customers write an email
- to an automatic `gawk' service that reads the email. It looks for
- keywords in the mail and assembles a reply email accordingly. By
+ * Another dialogue-oriented application (on the verge of ridicule) is
+ the email "support service." Troubled customers write an email to
+ an automatic 'gawk' service that reads the email. It looks for
+ keywords in the mail and assembles a reply email accordingly. By
carefully investigating the email header, and repeating these
keywords through the reply email, it is rather simple to give the
- customer a feeling that someone cares. Ideally, such a service
- would search a database of previous cases for solutions. If none
+ customer a feeling that someone cares. Ideally, such a service
+ would search a database of previous cases for solutions. If none
exists, the database could, for example, consist of all the
newsgroups, mailing lists and FAQs on the Internet.
@@ -1892,28 +1886,28 @@ File: gawkinet.info, Node: Some Applications and
Techniques, Next: Links, Pre
In this major node, we look at a number of self-contained scripts, with
an emphasis on concise networking. Along the way, we work towards
creating building blocks that encapsulate often needed functions of the
-networking world, show new techniques that broaden the scope of
-problems that can be solved with `gawk', and explore leading edge
-technology that may shape the future of networking.
+networking world, show new techniques that broaden the scope of problems
+that can be solved with 'gawk', and explore leading edge technology that
+may shape the future of networking.
We often refer to the site-independent core of the server that we
built in *note A Simple Web Server: Simple Server. When building new
and nontrivial servers, we always copy this building block and append
-new instances of the two functions `SetUpServer' and `HandleGET'.
+new instances of the two functions 'SetUpServer' and 'HandleGET'.
This makes a lot of sense, since this scheme of event-driven
-execution provides `gawk' with an interface to the most widely accepted
-standard for GUIs: the web browser. Now, `gawk' can rival even Tcl/Tk.
+execution provides 'gawk' with an interface to the most widely accepted
+standard for GUIs: the web browser. Now, 'gawk' can rival even Tcl/Tk.
- Tcl and `gawk' have much in common. Both are simple scripting
+ Tcl and 'gawk' have much in common. Both are simple scripting
languages that allow us to quickly solve problems with short programs.
-But Tcl has Tk on top of it, and `gawk' had nothing comparable up to
-now. While Tcl needs a large and ever-changing library (Tk, which was
-bound to the X Window System until recently), `gawk' needs just the
+But Tcl has Tk on top of it, and 'gawk' had nothing comparable up to
+now. While Tcl needs a large and ever-changing library (Tk, which was
+bound to the X Window System until recently), 'gawk' needs just the
networking interface and some kind of browser on the client's side.
Besides better portability, the most important advantage of this
approach (embracing well-established standards such HTTP and HTML) is
-that _we do not need to change the language_. We let others do the work
+that _we do not need to change the language_. We let others do the work
of fighting over protocols and standards. We can use HTML, JavaScript,
VRML, or whatever else comes along to do our work.
@@ -1936,22 +1930,22 @@ File: gawkinet.info, Node: PANIC, Next: GETURL,
Prev: Some Applications and T
3.1 PANIC: An Emergency Web Server
==================================
-At first glance, the `"Hello, world"' example in *note A Primitive Web
-Service: Primitive Service, seems useless. By adding just a few lines,
+At first glance, the '"Hello, world"' example in *note A Primitive Web
+Service: Primitive Service, seems useless. By adding just a few lines,
we can turn it into something useful.
The PANIC program tells everyone who connects that the local site is
-not working. When a web server breaks down, it makes a difference if
+not working. When a web server breaks down, it makes a difference if
customers get a strange "network unreachable" message, or a short
-message telling them that the server has a problem. In such an
-emergency, the hard disk and everything on it (including the regular
-web service) may be unavailable. Rebooting the web server off a
-diskette makes sense in this setting.
+message telling them that the server has a problem. In such an
+emergency, the hard disk and everything on it (including the regular web
+service) may be unavailable. Rebooting the web server off a diskette
+makes sense in this setting.
- To use the PANIC program as an emergency web server, all you need
-are the `gawk' executable and the program below on a diskette. By
-default, it connects to port 8080. A different value may be supplied on
-the command line:
+ To use the PANIC program as an emergency web server, all you need are
+the 'gawk' executable and the program below on a diskette. By default,
+it connects to port 8080. A different value may be supplied on the
+command line:
BEGIN {
RS = ORS = "\r\n"
@@ -1979,23 +1973,23 @@ File: gawkinet.info, Node: GETURL, Next: REMCONF,
Prev: PANIC, Up: Some Appl
================================
GETURL is a versatile building block for shell scripts that need to
-retrieve files from the Internet. It takes a web address as a
+retrieve files from the Internet. It takes a web address as a
command-line parameter and tries to retrieve the contents of this
-address. The contents are printed to standard output, while the header
-is printed to `/dev/stderr'. A surrounding shell script could analyze
-the contents and extract the text or the links. An ASCII browser could
+address. The contents are printed to standard output, while the header
+is printed to '/dev/stderr'. A surrounding shell script could analyze
+the contents and extract the text or the links. An ASCII browser could
be written around GETURL. But more interestingly, web robots are
straightforward to write on top of GETURL. On the Internet, you can find
-several programs of the same name that do the same job. They are usually
-much more complex internally and at least 10 times longer.
+several programs of the same name that do the same job. They are
+usually much more complex internally and at least 10 times longer.
At first, GETURL checks if it was called with exactly one web
address. Then, it checks if the user chose to use a special proxy
-server whose name is handed over in a variable. By default, it is
-assumed that the local machine serves as proxy. GETURL uses the `GET'
-method by default to access the web page. By handing over the name of a
-different method (such as `HEAD'), it is possible to choose a different
-behavior. With the `HEAD' method, the user does not receive the body of
+server whose name is handed over in a variable. By default, it is
+assumed that the local machine serves as proxy. GETURL uses the 'GET'
+method by default to access the web page. By handing over the name of a
+different method (such as 'HEAD'), it is possible to choose a different
+behavior. With the 'HEAD' method, the user does not receive the body of
the page content, but does receive the header:
BEGIN {
@@ -2025,8 +2019,8 @@ the page content, but does receive the header:
This program can be changed as needed, but be careful with the last
lines. Make sure transmission of binary data is not corrupted by
-additional line breaks. Even as it is now, the byte sequence
-`"\r\n\r\n"' would disappear if it were contained in binary data. Don't
+additional line breaks. Even as it is now, the byte sequence
+'"\r\n\r\n"' would disappear if it were contained in binary data. Don't
get caught in a trap when trying a quick fix on this one.
@@ -2036,13 +2030,12 @@ File: gawkinet.info, Node: REMCONF, Next: URLCHK,
Prev: GETURL, Up: Some App
=====================================================
Today, you often find powerful processors in embedded systems.
-Dedicated network routers and controllers for all kinds of machinery
-are examples of embedded systems. Processors like the Intel 80x86 or
-the AMD Elan are able to run multitasking operating systems, such as
-XINU or GNU/Linux in embedded PCs. These systems are small and usually
-do not have a keyboard or a display. Therefore it is difficult to set
-up their configuration. There are several widespread ways to set them
-up:
+Dedicated network routers and controllers for all kinds of machinery are
+examples of embedded systems. Processors like the Intel 80x86 or the
+AMD Elan are able to run multitasking operating systems, such as XINU or
+GNU/Linux in embedded PCs. These systems are small and usually do not
+have a keyboard or a display. Therefore it is difficult to set up their
+configuration. There are several widespread ways to set them up:
* DIP switches
@@ -2050,22 +2043,21 @@ up:
* Serial lines or some kind of keyboard
- * Network connections via `telnet' or SNMP
+ * Network connections via 'telnet' or SNMP
* HTTP connections with HTML GUIs
In this node, we look at a solution that uses HTTP connections to
control variables of an embedded system that are stored in a file.
-Since embedded systems have tight limits on resources like memory, it
-is difficult to employ advanced techniques such as SNMP and HTTP
-servers. `gawk' fits in quite nicely with its single executable which
-needs just a short script to start working. The following program
-stores the variables in a file, and a concurrent process in the
-embedded system may read the file. The program uses the
-site-independent part of the simple web server that we developed in
-*note A Web Service with Interaction: Interacting Service. As
-mentioned there, all we have to do is to write two new procedures
-`SetUpServer' and `HandleGET':
+Since embedded systems have tight limits on resources like memory, it is
+difficult to employ advanced techniques such as SNMP and HTTP servers.
+'gawk' fits in quite nicely with its single executable which needs just
+a short script to start working. The following program stores the
+variables in a file, and a concurrent process in the embedded system may
+read the file. The program uses the site-independent part of the simple
+web server that we developed in *note A Web Service with Interaction:
+Interacting Service. As mentioned there, all we have to do is to write
+two new procedures 'SetUpServer' and 'HandleGET':
function SetUpServer() {
TopHeader = "<HTML><title>Remote Configuration</title>"
@@ -2082,20 +2074,20 @@ mentioned there, all we have to do is to write two new
procedures
if (ConfigFile == "") ConfigFile = "config.asc"
}
- The function `SetUpServer' initializes the top level HTML texts as
-usual. It also initializes the name of the file that contains the
-configuration parameters and their values. In case the user supplies a
-name from the command line, that name is used. The file is expected to
-contain one parameter per line, with the name of the parameter in
-column one and the value in column two.
-
- The function `HandleGET' reflects the structure of the menu tree as
-usual. The first menu choice tells the user what this is all about. The
-second choice reads the configuration file line by line and stores the
-parameters and their values. Notice that the record separator for this
-file is `"\n"', in contrast to the record separator for HTTP. The third
-menu choice builds an HTML table to show the contents of the
-configuration file just read. The fourth choice does the real work of
+ The function 'SetUpServer' initializes the top level HTML texts as
+usual. It also initializes the name of the file that contains the
+configuration parameters and their values. In case the user supplies a
+name from the command line, that name is used. The file is expected to
+contain one parameter per line, with the name of the parameter in column
+one and the value in column two.
+
+ The function 'HandleGET' reflects the structure of the menu tree as
+usual. The first menu choice tells the user what this is all about.
+The second choice reads the configuration file line by line and stores
+the parameters and their values. Notice that the record separator for
+this file is '"\n"', in contrast to the record separator for HTTP. The
+third menu choice builds an HTML table to show the contents of the
+configuration file just read. The fourth choice does the real work of
changing parameters, and the last one just saves the configuration into
a file:
@@ -2140,10 +2132,10 @@ a file:
}
}
- We could also view the configuration file as a database. From this
+ We could also view the configuration file as a database. From this
point of view, the previous program acts like a primitive database
server. Real SQL database systems also make a service available by
-providing a TCP port that clients can connect to. But the application
+providing a TCP port that clients can connect to. But the application
level protocols they use are usually proprietary and also change from
time to time. This is also true for the protocol that MiniSQL uses.
@@ -2154,20 +2146,20 @@ File: gawkinet.info, Node: URLCHK, Next: WEBGRAB,
Prev: REMCONF, Up: Some Ap
======================================
Most people who make heavy use of Internet resources have a large
-bookmark file with pointers to interesting web sites. It is impossible
-to regularly check by hand if any of these sites have changed. A program
-is needed to automatically look at the headers of web pages and tell
-which ones have changed. URLCHK does the comparison after using GETURL
-with the `HEAD' method to retrieve the header.
+bookmark file with pointers to interesting web sites. It is impossible
+to regularly check by hand if any of these sites have changed. A
+program is needed to automatically look at the headers of web pages and
+tell which ones have changed. URLCHK does the comparison after using
+GETURL with the 'HEAD' method to retrieve the header.
Like GETURL, this program first checks that it is called with exactly
-one command-line parameter. URLCHK also takes the same command-line
-variables `Proxy' and `ProxyPort' as GETURL, because these variables
-are handed over to GETURL for each URL that gets checked. The one and
-only parameter is the name of a file that contains one line for each
-URL. In the first column, we find the URL, and the second and third
-columns hold the length of the URL's body when checked for the two last
-times. Now, we follow this plan:
+one command-line parameter. URLCHK also takes the same command-line
+variables 'Proxy' and 'ProxyPort' as GETURL, because these variables are
+handed over to GETURL for each URL that gets checked. The one and only
+parameter is the name of a file that contains one line for each URL. In
+the first column, we find the URL, and the second and third columns hold
+the length of the URL's body when checked for the two last times. Now,
+we follow this plan:
1. Read the URLs from the file and remember their most recent lengths
@@ -2177,11 +2169,11 @@ times. Now, we follow this plan:
4. If the most recent and the new length differ, tell the user
- It may seem a bit peculiar to read the URLs from a file together
-with their two most recent lengths, but this approach has several
-advantages. You can call the program again and again with the same
-file. After running the program, you can regenerate the changed URLs by
-extracting those lines that differ in their second and third columns:
+ It may seem a bit peculiar to read the URLs from a file together with
+their two most recent lengths, but this approach has several advantages.
+You can call the program again and again with the same file. After
+running the program, you can regenerate the changed URLs by extracting
+those lines that differ in their second and third columns:
BEGIN {
if (ARGC != 2) {
@@ -2214,18 +2206,18 @@ extracting those lines that differ in their second and
third columns:
Another thing that may look strange is the way GETURL is called.
Before calling GETURL, we have to check if the proxy variables need to
-be passed on. If so, we prepare strings that will become part of the
-command line later. In `GetHeader', we store these strings together
-with the longest part of the command line. Later, in the loop over the
-URLs, `GetHeader' is appended with the URL and a redirection operator
-to form the command that reads the URL's header over the Internet.
-GETURL always produces the headers over `/dev/stderr'. That is the
-reason why we need the redirection operator to have the header piped in.
+be passed on. If so, we prepare strings that will become part of the
+command line later. In 'GetHeader', we store these strings together
+with the longest part of the command line. Later, in the loop over the
+URLs, 'GetHeader' is appended with the URL and a redirection operator to
+form the command that reads the URL's header over the Internet. GETURL
+always produces the headers over '/dev/stderr'. That is the reason why
+we need the redirection operator to have the header piped in.
This program is not perfect because it assumes that changing URLs
-results in changed lengths, which is not necessarily true. A more
+results in changed lengths, which is not necessarily true. A more
advanced approach is to look at some other header line that holds time
-information. But, as always when things get a bit more complicated,
+information. But, as always when things get a bit more complicated,
this is left as an exercise to the reader.
@@ -2246,44 +2238,44 @@ the Bourne shell:
print command
}
- Notice that the regular expression for URLs is rather crude. A
-precise regular expression is much more complex. But this one works
-rather well. One problem is that it is unable to find internal links of
-an HTML document. Another problem is that `ftp', `telnet', `news',
-`mailto', and other kinds of links are missing in the regular
+ Notice that the regular expression for URLs is rather crude. A
+precise regular expression is much more complex. But this one works
+rather well. One problem is that it is unable to find internal links of
+an HTML document. Another problem is that 'ftp', 'telnet', 'news',
+'mailto', and other kinds of links are missing in the regular
expression. However, it is straightforward to add them, if doing so is
necessary for other tasks.
- This program reads an HTML file and prints all the HTTP links that
-it finds. It relies on `gawk''s ability to use regular expressions as
-record separators. With `RS' set to a regular expression that matches
+ This program reads an HTML file and prints all the HTTP links that it
+finds. It relies on 'gawk''s ability to use regular expressions as
+record separators. With 'RS' set to a regular expression that matches
links, the second action is executed each time a non-empty link is
-found. We can find the matching link itself in `RT'.
+found. We can find the matching link itself in 'RT'.
- The action could use the `system' function to let another GETURL
+ The action could use the 'system' function to let another GETURL
retrieve the page, but here we use a different approach. This simple
-program prints shell commands that can be piped into `sh' for
-execution. This way it is possible to first extract the links, wrap
-shell commands around them, and pipe all the shell commands into a
-file. After editing the file, execution of the file retrieves exactly
-those files that we really need. In case we do not want to edit, we can
-retrieve all the pages like this:
+program prints shell commands that can be piped into 'sh' for execution.
+This way it is possible to first extract the links, wrap shell commands
+around them, and pipe all the shell commands into a file. After editing
+the file, execution of the file retrieves exactly those files that we
+really need. In case we do not want to edit, we can retrieve all the
+pages like this:
gawk -f geturl.awk http://www.suse.de | gawk -f webgrab.awk | sh
After this, you will find the contents of all referenced documents in
-files named `doc*.html' even if they do not contain HTML code. The
-most annoying thing is that we always have to pass the proxy to GETURL.
-If you do not like to see the headers of the web pages appear on the
-screen, you can redirect them to `/dev/null'. Watching the headers
+files named 'doc*.html' even if they do not contain HTML code. The most
+annoying thing is that we always have to pass the proxy to GETURL. If
+you do not like to see the headers of the web pages appear on the
+screen, you can redirect them to '/dev/null'. Watching the headers
appear can be quite interesting, because it reveals interesting details
such as which web server the companies use. Now, it is clear how the
-clever marketing people use web robots to determine the market shares
-of Microsoft and Netscape in the web server market.
+clever marketing people use web robots to determine the market shares of
+Microsoft and Netscape in the web server market.
Port 80 of any web server is like a small hole in a repellent
firewall. After attaching a browser to port 80, we usually catch a
-glimpse of the bright side of the server (its home page). With a tool
+glimpse of the bright side of the server (its home page). With a tool
like GETURL at hand, we are able to discover some of the more concealed
or even "indecent" services (i.e., lacking conformity to standards of
quality). It can be exciting to see the fancy CGI scripts that lie
@@ -2295,14 +2287,14 @@ there, revealing the inner workings of the server,
ready to be called:
some servers give you a directory listing of the CGI files.
Knowing the names, you can try to call some of them and watch for
- useful results. Sometimes there are executables in such directories
- (such as Perl interpreters) that you may call remotely. If there
- are subdirectories with configuration data of the web server, this
- can also be quite interesting to read.
+ useful results. Sometimes there are executables in such
+ directories (such as Perl interpreters) that you may call remotely.
+ If there are subdirectories with configuration data of the web
+ server, this can also be quite interesting to read.
* The well-known Apache web server usually has its CGI files in the
- directory `/cgi-bin'. There you can often find the scripts
- `test-cgi' and `printenv'. Both tell you some things about the
+ directory '/cgi-bin'. There you can often find the scripts
+ 'test-cgi' and 'printenv'. Both tell you some things about the
current connection and the installation of the web server. Just
call:
@@ -2311,10 +2303,10 @@ there, revealing the inner workings of the server,
ready to be called:
* Sometimes it is even possible to retrieve system files like the web
server's log file--possibly containing customer data--or even the
- file `/etc/passwd'. (We don't recommend this!)
+ file '/etc/passwd'. (We don't recommend this!)
- *Caution:* Although this may sound funny or simply irrelevant, we
-are talking about severe security holes. Try to explore your own system
+ *Caution:* Although this may sound funny or simply irrelevant, we are
+talking about severe security holes. Try to explore your own system
this way and make sure that none of the above reveals too much
information about your system.
@@ -2325,27 +2317,27 @@ File: gawkinet.info, Node: STATIST, Next: MAZE,
Prev: WEBGRAB, Up: Some Appl
================================================
In the HTTP server examples we've shown thus far, we never present an
-image to the browser and its user. Presenting images is one task.
+image to the browser and its user. Presenting images is one task.
Generating images that reflect some user input and presenting these
-dynamically generated images is another. In this node, we use GNUPlot
-for generating `.png', `.ps', or `.gif' files.(1)
+dynamically generated images is another. In this node, we use GNUPlot
+for generating '.png', '.ps', or '.gif' files.(1)
The program we develop takes the statistical parameters of two
-samples and computes the t-test statistics. As a result, we get the
+samples and computes the t-test statistics. As a result, we get the
probabilities that the means and the variances of both samples are the
-same. In order to let the user check plausibility, the program presents
-an image of the distributions. The statistical computation follows
-`Numerical Recipes in C: The Art of Scientific Computing' by William H.
+same. In order to let the user check plausibility, the program presents
+an image of the distributions. The statistical computation follows
+'Numerical Recipes in C: The Art of Scientific Computing' by William H.
Press, Saul A. Teukolsky, William T. Vetterling, and Brian P. Flannery.
-Since `gawk' does not have a built-in function for the computation of
-the beta function, we use the `ibeta' function of GNUPlot. As a side
-effect, we learn how to use GNUPlot as a sophisticated calculator. The
-comparison of means is done as in `tutest', paragraph 14.2, page 613,
-and the comparison of variances is done as in `ftest', page 611 in
-`Numerical Recipes'.
+Since 'gawk' does not have a built-in function for the computation of
+the beta function, we use the 'ibeta' function of GNUPlot. As a side
+effect, we learn how to use GNUPlot as a sophisticated calculator. The
+comparison of means is done as in 'tutest', paragraph 14.2, page 613,
+and the comparison of variances is done as in 'ftest', page 611 in
+'Numerical Recipes'.
As usual, we take the site-independent code for servers and append
-our own functions `SetUpServer' and `HandleGET':
+our own functions 'SetUpServer' and 'HandleGET':
function SetUpServer() {
TopHeader = "<HTML><title>Statistics with GAWK</title>"
@@ -2360,25 +2352,25 @@ our own functions `SetUpServer' and `HandleGET':
m1=m2=0; v1=v2=1; n1=n2=10
}
- Here, you see the menu structure that the user sees. Later, we will
-see how the program structure of the `HandleGET' function reflects the
-menu structure. What is missing here is the link for the image we
-generate. In an event-driven environment, request, generation, and
+ Here, you see the menu structure that the user sees. Later, we will
+see how the program structure of the 'HandleGET' function reflects the
+menu structure. What is missing here is the link for the image we
+generate. In an event-driven environment, request, generation, and
delivery of images are separated.
- Notice the way we initialize the `GnuPlot' command string for the
-pipe. By default, GNUPlot outputs the generated image via standard
-output, as well as the results of `print'(ed) calculations via standard
+ Notice the way we initialize the 'GnuPlot' command string for the
+pipe. By default, GNUPlot outputs the generated image via standard
+output, as well as the results of 'print'(ed) calculations via standard
error. The redirection causes standard error to be mixed into standard
-output, enabling us to read results of calculations with `getline'. By
+output, enabling us to read results of calculations with 'getline'. By
initializing the statistical parameters with some meaningful defaults,
we make sure the user gets an image the first time he uses the program.
- Following is the rather long function `HandleGET', which implements
+ Following is the rather long function 'HandleGET', which implements
the contents of this service by reacting to the different kinds of
-requests from the browser. Before you start playing with this script,
+requests from the browser. Before you start playing with this script,
make sure that your browser supports JavaScript and that it also has
-this option switched on. The script uses a short snippet of JavaScript
+this option switched on. The script uses a short snippet of JavaScript
code for delayed opening of a window with an image. A more detailed
explanation follows:
@@ -2457,105 +2449,100 @@ explanation follows:
}
As usual, we give a short description of the service in the first
-menu choice. The third menu choice shows us that generation and
-presentation of an image are two separate actions. While the latter
+menu choice. The third menu choice shows us that generation and
+presentation of an image are two separate actions. While the latter
takes place quite instantly in the third menu choice, the former takes
-place in the much longer second choice. Image data passes from the
-generating action to the presenting action via the variable `Image'
-that contains a complete `.png' image, which is otherwise stored in a
-file. If you prefer `.ps' or `.gif' images over the default `.png'
-images, you may select these options by uncommenting the appropriate
-lines. But remember to do so in two places: when telling GNUPlot which
-kind of images to generate, and when transmitting the image at the end
-of the program.
-
- Looking at the end of the program, the way we pass the
-`Content-type' to the browser is a bit unusual. It is appended to the
-`OK' of the first header line to make sure the type information becomes
-part of the header. The other variables that get transmitted across
-the network are made empty, because in this case we do not have an HTML
-document to transmit, but rather raw image data to contain in the body.
-
- Most of the work is done in the second menu choice. It starts with a
-strange JavaScript code snippet. When first implementing this server,
-we used a short `"<IMG SRC=" MyPrefix "/Image>"' here. But then
+place in the much longer second choice. Image data passes from the
+generating action to the presenting action via the variable 'Image' that
+contains a complete '.png' image, which is otherwise stored in a file.
+If you prefer '.ps' or '.gif' images over the default '.png' images, you
+may select these options by uncommenting the appropriate lines. But
+remember to do so in two places: when telling GNUPlot which kind of
+images to generate, and when transmitting the image at the end of the
+program.
+
+ Looking at the end of the program, the way we pass the 'Content-type'
+to the browser is a bit unusual. It is appended to the 'OK' of the
+first header line to make sure the type information becomes part of the
+header. The other variables that get transmitted across the network are
+made empty, because in this case we do not have an HTML document to
+transmit, but rather raw image data to contain in the body.
+
+ Most of the work is done in the second menu choice. It starts with a
+strange JavaScript code snippet. When first implementing this server,
+we used a short '"<IMG SRC=" MyPrefix "/Image>"' here. But then
browsers got smarter and tried to improve on speed by requesting the
-image and the HTML code at the same time. When doing this, the browser
+image and the HTML code at the same time. When doing this, the browser
tries to build up a connection for the image request while the request
-for the HTML text is not yet completed. The browser tries to connect to
-the `gawk' server on port 8080 while port 8080 is still in use for
-transmission of the HTML text. The connection for the image cannot be
+for the HTML text is not yet completed. The browser tries to connect to
+the 'gawk' server on port 8080 while port 8080 is still in use for
+transmission of the HTML text. The connection for the image cannot be
built up, so the image appears as "broken" in the browser window. We
-solved this problem by telling the browser to open a separate window
-for the image, but only after a delay of 1000 milliseconds. By this
-time, the server should be ready for serving the next request.
-
- But there is one more subtlety in the JavaScript code. Each time
-the JavaScript code opens a window for the image, the name of the image
-is appended with a timestamp (`systime'). Why this constant change of
-name for the image? Initially, we always named the image `Image', but
-then the Netscape browser noticed the name had _not_ changed since the
+solved this problem by telling the browser to open a separate window for
+the image, but only after a delay of 1000 milliseconds. By this time,
+the server should be ready for serving the next request.
+
+ But there is one more subtlety in the JavaScript code. Each time the
+JavaScript code opens a window for the image, the name of the image is
+appended with a timestamp ('systime'). Why this constant change of name
+for the image? Initially, we always named the image 'Image', but then
+the Netscape browser noticed the name had _not_ changed since the
previous request and displayed the previous image (caching behavior).
The server core is implemented so that browsers are told _not_ to cache
-anything. Obviously HTTP requests do not always work as expected. One
+anything. Obviously HTTP requests do not always work as expected. One
way to circumvent the cache of such overly smart browsers is to change
-the name of the image with each request. These three lines of JavaScript
-caused us a lot of trouble.
+the name of the image with each request. These three lines of
+JavaScript caused us a lot of trouble.
- The rest can be broken down into two phases. At first, we check if
-there are statistical parameters. When the program is first started,
+ The rest can be broken down into two phases. At first, we check if
+there are statistical parameters. When the program is first started,
there usually are no parameters because it enters the page coming from
-the top menu. Then, we only have to present the user a form that he
-can use to change statistical parameters and submit them. Subsequently,
-the submission of the form causes the execution of the first phase
-because _now_ there _are_ parameters to handle.
+the top menu. Then, we only have to present the user a form that he can
+use to change statistical parameters and submit them. Subsequently, the
+submission of the form causes the execution of the first phase because
+_now_ there _are_ parameters to handle.
Now that we have parameters, we know there will be an image
-available. Therefore we insert the JavaScript code here to initiate
-the opening of the image in a separate window. Then, we prepare some
+available. Therefore we insert the JavaScript code here to initiate the
+opening of the image in a separate window. Then, we prepare some
variables that will be passed to GNUPlot for calculation of the
-probabilities. Prior to reading the results, we must temporarily change
-`RS' because GNUPlot separates lines with newlines. After instructing
-GNUPlot to generate a `.png' (or `.ps' or `.gif') image, we initiate
-the insertion of some text, explaining the resulting probabilities. The
-final `plot' command actually generates the image data. This raw binary
+probabilities. Prior to reading the results, we must temporarily change
+'RS' because GNUPlot separates lines with newlines. After instructing
+GNUPlot to generate a '.png' (or '.ps' or '.gif') image, we initiate the
+insertion of some text, explaining the resulting probabilities. The
+final 'plot' command actually generates the image data. This raw binary
has to be read in carefully without adding, changing, or deleting a
-single byte. Hence the unusual initialization of `Image' and completion
-with a `while' loop.
+single byte. Hence the unusual initialization of 'Image' and completion
+with a 'while' loop.
When using this server, it soon becomes clear that it is far from
-being perfect. It mixes source code of six scripting languages or
+being perfect. It mixes source code of six scripting languages or
protocols:
- * GNU `awk' implements a server for the protocol:
-
+ * GNU 'awk' implements a server for the protocol:
* HTTP which transmits:
-
* HTML text which contains a short piece of:
-
* JavaScript code opening a separate window.
-
* A Bourne shell script is used for piping commands into:
-
* GNUPlot to generate the image to be opened.
After all this work, the GNUPlot image opens in the JavaScript window
where it can be viewed by the user.
- It is probably better not to mix up so many different languages.
-The result is not very readable. Furthermore, the statistical part of
-the server does not take care of invalid input. Among others, using
+ It is probably better not to mix up so many different languages. The
+result is not very readable. Furthermore, the statistical part of the
+server does not take care of invalid input. Among others, using
negative variances will cause invalid results.
---------- Footnotes ----------
(1) Due to licensing problems, the default installation of GNUPlot
-disables the generation of `.gif' files. If your installed version
-does not accept `set term gif', just download and install the most
-recent version of GNUPlot and the GD library
-(http://www.boutell.com/gd/) by Thomas Boutell. Otherwise you still
-have the chance to generate some ASCII-art style images with GNUPlot by
-using `set term dumb'. (We tried it and it worked.)
+disables the generation of '.gif' files. If your installed version does
+not accept 'set term gif', just download and install the most recent
+version of GNUPlot and the GD library (http://www.boutell.com/gd/) by
+Thomas Boutell. Otherwise you still have the chance to generate some
+ASCII-art style images with GNUPlot by using 'set term dumb'. (We tried
+it and it worked.)
File: gawkinet.info, Node: MAZE, Next: MOBAGWHO, Prev: STATIST, Up: Some
Applications and Techniques
@@ -2566,19 +2553,19 @@ File: gawkinet.info, Node: MAZE, Next: MOBAGWHO,
Prev: STATIST, Up: Some App
In the long run, every program becomes rococo, and then rubble.
Alan Perlis
- By now, we know how to present arbitrary `Content-type's to a
+ By now, we know how to present arbitrary 'Content-type's to a
browser. In this node, our server will present a 3D world to our
browser. The 3D world is described in a scene description language
(VRML, Virtual Reality Modeling Language) that allows us to travel
-through a perspective view of a 2D maze with our browser. Browsers with
-a VRML plugin enable exploration of this technology. We could do one of
-those boring `Hello world' examples here, that are usually presented
+through a perspective view of a 2D maze with our browser. Browsers with
+a VRML plugin enable exploration of this technology. We could do one of
+those boring 'Hello world' examples here, that are usually presented
when introducing novices to VRML. If you have never written any VRML
-code, have a look at the VRML FAQ. Presenting a static VRML scene is a
-bit trivial; in order to expose `gawk''s new capabilities, we will
-present a dynamically generated VRML scene. The function `SetUpServer'
+code, have a look at the VRML FAQ. Presenting a static VRML scene is a
+bit trivial; in order to expose 'gawk''s new capabilities, we will
+present a dynamically generated VRML scene. The function 'SetUpServer'
is very simple because it only sets the default HTML page and
-initializes the random number generator. As usual, the surrounding
+initializes the random number generator. As usual, the surrounding
server lets you browse the maze.
function SetUpServer() {
@@ -2593,15 +2580,15 @@ server lets you browse the maze.
srand()
}
- The function `HandleGET' is a bit longer because it first computes
+ The function 'HandleGET' is a bit longer because it first computes
the maze and afterwards generates the VRML code that is sent across the
-network. As shown in the STATIST example (*note STATIST::), we set the
+network. As shown in the STATIST example (*note STATIST::), we set the
type of the content to VRML and then store the VRML representation of
-the maze as the page content. We assume that the maze is stored in a 2D
-array. Initially, the maze consists of walls only. Then, we add an
+the maze as the page content. We assume that the maze is stored in a 2D
+array. Initially, the maze consists of walls only. Then, we add an
entry and an exit to the maze and let the rest of the work be done by
-the function `MakeMaze'. Now, only the wall fields are left in the
-maze. By iterating over the these fields, we generate one line of VRML
+the function 'MakeMaze'. Now, only the wall fields are left in the
+maze. By iterating over the these fields, we generate one line of VRML
code for each wall field.
function HandleGET() {
@@ -2650,25 +2637,25 @@ code for each wall field.
}
}
- Finally, we have a look at `MakeMaze', the function that generates
-the `Maze' array. When entered, this function assumes that the array
+ Finally, we have a look at 'MakeMaze', the function that generates
+the 'Maze' array. When entered, this function assumes that the array
has been initialized so that each element represents a wall element and
-the maze is initially full of wall elements. Only the entrance and the
-exit of the maze should have been left free. The parameters of the
+the maze is initially full of wall elements. Only the entrance and the
+exit of the maze should have been left free. The parameters of the
function tell us which element must be marked as not being a wall.
-After this, we take a look at the four neighboring elements and
-remember which we have already treated. Of all the neighboring
-elements, we take one at random and walk in that direction. Therefore,
-the wall element in that direction has to be removed and then, we call
-the function recursively for that element. The maze is only completed
-if we iterate the above procedure for _all_ neighboring elements (in
-random order) and for our present element by recursively calling the
-function for the present element. This last iteration could have been
-done in a loop, but it is done much simpler recursively.
+After this, we take a look at the four neighboring elements and remember
+which we have already treated. Of all the neighboring elements, we take
+one at random and walk in that direction. Therefore, the wall element
+in that direction has to be removed and then, we call the function
+recursively for that element. The maze is only completed if we iterate
+the above procedure for _all_ neighboring elements (in random order) and
+for our present element by recursively calling the function for the
+present element. This last iteration could have been done in a loop,
+but it is done much simpler recursively.
Notice that elements with coordinates that are both odd are assumed
to be on our way through the maze and the generating process cannot
-terminate as long as there is such an element not being `delete'd. All
+terminate as long as there is such an element not being 'delete'd. All
other elements are potentially part of the wall.
function MakeMaze(x, y) {
@@ -2702,51 +2689,51 @@ File: gawkinet.info, Node: MOBAGWHO, Next: STOXPRED,
Prev: MAZE, Up: Some Ap
C. A. R. Hoare
A "mobile agent" is a program that can be dispatched from a computer
-and transported to a remote server for execution. This is called
+and transported to a remote server for execution. This is called
"migration", which means that a process on another system is started
-that is independent from its originator. Ideally, it wanders through a
-network while working for its creator or owner. In places like the UMBC
+that is independent from its originator. Ideally, it wanders through a
+network while working for its creator or owner. In places like the UMBC
Agent Web, people are quite confident that (mobile) agents are a
software engineering paradigm that enables us to significantly increase
-the efficiency of our work. Mobile agents could become the mediators
-between users and the networking world. For an unbiased view at this
-technology, see the remarkable paper `Mobile Agents: Are they a good
+the efficiency of our work. Mobile agents could become the mediators
+between users and the networking world. For an unbiased view at this
+technology, see the remarkable paper 'Mobile Agents: Are they a good
idea?'.(1)
- When trying to migrate a process from one system to another, a
-server process is needed on the receiving side. Depending on the kind
-of server process, several ways of implementation come to mind. How
-the process is implemented depends upon the kind of server process:
+ When trying to migrate a process from one system to another, a server
+process is needed on the receiving side. Depending on the kind of
+server process, several ways of implementation come to mind. How the
+process is implemented depends upon the kind of server process:
* HTTP can be used as the protocol for delivery of the migrating
- process. In this case, we use a common web server as the receiving
- server process. A universal CGI script mediates between migrating
+ process. In this case, we use a common web server as the receiving
+ server process. A universal CGI script mediates between migrating
process and web server. Each server willing to accept migrating
- agents makes this universal service available. HTTP supplies the
- `POST' method to transfer some data to a file on the web server.
- When a CGI script is called remotely with the `POST' method
- instead of the usual `GET' method, data is transmitted from the
- client process to the standard input of the server's CGI script.
- So, to implement a mobile agent, we must not only write the agent
- program to start on the client side, but also the CGI script to
- receive the agent on the server side.
-
- * The `PUT' method can also be used for migration. HTTP does not
- require a CGI script for migration via `PUT'. However, with common
+ agents makes this universal service available. HTTP supplies the
+ 'POST' method to transfer some data to a file on the web server.
+ When a CGI script is called remotely with the 'POST' method instead
+ of the usual 'GET' method, data is transmitted from the client
+ process to the standard input of the server's CGI script. So, to
+ implement a mobile agent, we must not only write the agent program
+ to start on the client side, but also the CGI script to receive the
+ agent on the server side.
+
+ * The 'PUT' method can also be used for migration. HTTP does not
+ require a CGI script for migration via 'PUT'. However, with common
web servers there is no advantage to this solution, because web
servers such as Apache require explicit activation of a special
- `PUT' script.
+ 'PUT' script.
- * `Agent Tcl' pursues a different course; it relies on a dedicated
+ * 'Agent Tcl' pursues a different course; it relies on a dedicated
server process with a dedicated protocol specialized for receiving
mobile agents.
Our agent example abuses a common web server as a migration tool.
So, it needs a universal CGI script on the receiving side (the web
-server). The receiving script is activated with a `POST' request when
-placed into a location like `/httpd/cgi-bin/PostAgent.sh'. Make sure
-that the server system uses a version of `gawk' that supports network
-access (Version 3.1 or later; verify with `gawk --version').
+server). The receiving script is activated with a 'POST' request when
+placed into a location like '/httpd/cgi-bin/PostAgent.sh'. Make sure
+that the server system uses a version of 'gawk' that supports network
+access (Version 3.1 or later; verify with 'gawk --version').
#!/bin/sh
MobAg=/tmp/MobileAgent.$$
@@ -2758,34 +2745,34 @@ access (Version 3.1 or later; verify with `gawk
--version').
gawk 'BEGIN { print "\r\nAgent started" }'
rm $MobAg # delete script file of agent
- By making its process id (`$$') part of the unique file name, the
+ By making its process id ('$$') part of the unique file name, the
script avoids conflicts between concurrent instances of the script.
First, all lines from standard input (the mobile agent's source code)
-are copied into this unique file. Then, the agent is started as a
+are copied into this unique file. Then, the agent is started as a
concurrent process and a short message reporting this fact is sent to
the submitting client. Finally, the script file of the mobile agent is
-removed because it is no longer needed. Although it is a short script,
+removed because it is no longer needed. Although it is a short script,
there are several noteworthy points:
Security
- _There is none_. In fact, the CGI script should never be made
+ _There is none_. In fact, the CGI script should never be made
available on a server that is part of the Internet because everyone
- would be allowed to execute arbitrary commands with it. This
+ would be allowed to execute arbitrary commands with it. This
behavior is acceptable only when performing rapid prototyping.
Self-Reference
Each migrating instance of an agent is started in a way that
enables it to read its own source code from standard input and use
- the code for subsequent migrations. This is necessary because it
- needs to treat the agent's code as data to transmit. `gawk' is not
- the ideal language for such a job. Lisp and Tcl are more suitable
+ the code for subsequent migrations. This is necessary because it
+ needs to treat the agent's code as data to transmit. 'gawk' is not
+ the ideal language for such a job. Lisp and Tcl are more suitable
because they do not make a distinction between program code and
data.
Independence
After migration, the agent is not linked to its former home in any
- way. By reporting `Agent started', it waves "Goodbye" to its
- origin. The originator may choose to terminate or not.
+ way. By reporting 'Agent started', it waves "Goodbye" to its
+ origin. The originator may choose to terminate or not.
The originating agent itself is started just like any other
command-line script, and reports the results on standard output. By
@@ -2793,10 +2780,10 @@ letting the name of the original host migrate with the
agent, the agent
that migrates to a host far away from its origin can report the result
back home. Having arrived at the end of the journey, the agent
establishes a connection and reports the results. This is the reason
-for determining the name of the host with `uname -n' and storing it in
-`MyOrigin' for later use. We may also set variables with the `-v'
-option from the command line. This interactivity is only of importance
-in the context of starting a mobile agent; therefore this `BEGIN'
+for determining the name of the host with 'uname -n' and storing it in
+'MyOrigin' for later use. We may also set variables with the '-v'
+option from the command line. This interactivity is only of importance
+in the context of starting a mobile agent; therefore this 'BEGIN'
pattern and its action do not take part in migration:
BEGIN {
@@ -2815,15 +2802,15 @@ pattern and its action do not take part in migration:
}
}
- Since `gawk' cannot manipulate and transmit parts of the program
-directly, the source code is read and stored in strings. Therefore,
-the program scans itself for the beginning and the ending of functions.
-Each line in between is appended to the code string until the end of
-the function has been reached. A special case is this part of the
-program itself. It is not a function. Placing a similar framework
-around it causes it to be treated like a function. Notice that this
-mechanism works for all the functions of the source code, but it cannot
-guarantee that the order of the functions is preserved during migration:
+ Since 'gawk' cannot manipulate and transmit parts of the program
+directly, the source code is read and stored in strings. Therefore, the
+program scans itself for the beginning and the ending of functions.
+Each line in between is appended to the code string until the end of the
+function has been reached. A special case is this part of the program
+itself. It is not a function. Placing a similar framework around it
+causes it to be treated like a function. Notice that this mechanism
+works for all the functions of the source code, but it cannot guarantee
+that the order of the functions is preserved during migration:
#ReadMySelf
/^function / { FUNC = $2 }
@@ -2835,10 +2822,10 @@ guarantee that the order of the functions is preserved
during migration:
The web server code in *note A Web Service with Interaction:
Interacting Service, was first developed as a site-independent core.
-Likewise, the `gawk'-based mobile agent starts with an
-agent-independent core, to which can be appended application-dependent
-functions. What follows is the only application-independent function
-needed for the mobile agent:
+Likewise, the 'gawk'-based mobile agent starts with an agent-independent
+core, to which can be appended application-dependent functions. What
+follows is the only application-independent function needed for the
+mobile agent:
function migrate(Destination, MobCode, Label) {
MOBVAR["Label"] = Label
@@ -2859,54 +2846,54 @@ needed for the mobile agent:
close(HttpService)
}
- The `migrate' function prepares the aforementioned strings
-containing the program code and transmits them to a server. A
-consequence of this modular approach is that the `migrate' function
-takes some parameters that aren't needed in this application, but that
-will be in future ones. Its mandatory parameter `Destination' holds the
-name (or IP address) of the server that the agent wants as a host for
-its code. The optional parameter `MobCode' may contain some `gawk' code
-that is inserted during migration in front of all other code. The
-optional parameter `Label' may contain a string that tells the agent
-what to do in program execution after arrival at its new home site. One
-of the serious obstacles in implementing a framework for mobile agents
-is that it does not suffice to migrate the code. It is also necessary
-to migrate the state of execution of the agent. In contrast to `Agent
-Tcl', this program does not try to migrate the complete set of
-variables. The following conventions are used:
+ The 'migrate' function prepares the aforementioned strings containing
+the program code and transmits them to a server. A consequence of this
+modular approach is that the 'migrate' function takes some parameters
+that aren't needed in this application, but that will be in future ones.
+Its mandatory parameter 'Destination' holds the name (or IP address) of
+the server that the agent wants as a host for its code. The optional
+parameter 'MobCode' may contain some 'gawk' code that is inserted during
+migration in front of all other code. The optional parameter 'Label'
+may contain a string that tells the agent what to do in program
+execution after arrival at its new home site. One of the serious
+obstacles in implementing a framework for mobile agents is that it does
+not suffice to migrate the code. It is also necessary to migrate the
+state of execution of the agent. In contrast to 'Agent Tcl', this
+program does not try to migrate the complete set of variables. The
+following conventions are used:
* Each variable in an agent program is local to the current host and
does _not_ migrate.
- * The array `MOBFUN' shown above is an exception. It is handled by
- the function `migrate' and does migrate with the application.
+ * The array 'MOBFUN' shown above is an exception. It is handled by
+ the function 'migrate' and does migrate with the application.
- * The other exception is the array `MOBVAR'. Each variable that
+ * The other exception is the array 'MOBVAR'. Each variable that
takes part in migration has to be an element of this array.
- `migrate' also takes care of this.
+ 'migrate' also takes care of this.
- Now it's clear what happens to the `Label' parameter of the function
-`migrate'. It is copied into `MOBVAR["Label"]' and travels alongside
-the other data. Since travelling takes place via HTTP, records must be
-separated with `"\r\n"' in `RS' and `ORS' as usual. The code assembly
+ Now it's clear what happens to the 'Label' parameter of the function
+'migrate'. It is copied into 'MOBVAR["Label"]' and travels alongside
+the other data. Since travelling takes place via HTTP, records must be
+separated with '"\r\n"' in 'RS' and 'ORS' as usual. The code assembly
for migration takes place in three steps:
- * Iterate over `MOBFUN' to collect all functions verbatim.
+ * Iterate over 'MOBFUN' to collect all functions verbatim.
- * Prepare a `BEGIN' pattern and put assignments to mobile variables
+ * Prepare a 'BEGIN' pattern and put assignments to mobile variables
into the action part.
* Transmission itself resembles GETURL: the header with the request
- and the `Content-length' is followed by the body. In case there is
+ and the 'Content-length' is followed by the body. In case there is
any reply over the network, it is read completely and echoed to
standard output to avoid irritating the server.
- The application-independent framework is now almost complete. What
-follows is the `END' pattern that is executed when the mobile agent has
-finished reading its own code. First, it checks whether it is already
-running on a remote host or not. In case initialization has not yet
-taken place, it starts `MyInit'. Otherwise (later, on a remote host), it
-starts `MyJob':
+ The application-independent framework is now almost complete. What
+follows is the 'END' pattern that is executed when the mobile agent has
+finished reading its own code. First, it checks whether it is already
+running on a remote host or not. In case initialization has not yet
+taken place, it starts 'MyInit'. Otherwise (later, on a remote host),
+it starts 'MyJob':
END {
if (ARGC != 2) exit # stop when called with wrong parameters
@@ -2917,7 +2904,7 @@ starts `MyJob':
}
All that's left to extend the framework into a complete application
-is to write two application-specific functions: `MyInit' and `MyJob'.
+is to write two application-specific functions: 'MyInit' and 'MyJob'.
Keep in mind that the former is executed once on the originating host,
while the latter is executed after each migration:
@@ -2932,11 +2919,11 @@ while the latter is executed after each migration:
}
As mentioned earlier, this agent takes the name of its origin
-(`MyOrigin') with it. Then, it takes the name of its first destination
-and goes there for further work. Notice that this name has the port
-number of the web server appended to the name of the server, because
-the function `migrate' needs it this way to create the `HttpService'
-variable. Finally, it waits for the result to arrive. The `MyJob'
+('MyOrigin') with it. Then, it takes the name of its first destination
+and goes there for further work. Notice that this name has the port
+number of the web server appended to the name of the server, because the
+function 'migrate' needs it this way to create the 'HttpService'
+variable. Finally, it waits for the result to arrive. The 'MyJob'
function runs on the remote host:
function MyJob() {
@@ -2956,23 +2943,23 @@ function runs on the remote host:
}
}
- After migrating, the first thing to do in `MyJob' is to delete the
-name of the current host from the list of hosts to visit. Now, it is
+ After migrating, the first thing to do in 'MyJob' is to delete the
+name of the current host from the list of hosts to visit. Now, it is
time to start the real work by appending the host's name to the result
string, and reading line by line who is logged in on this host. A very
-annoying circumstance is the fact that the elements of `MOBVAR' cannot
-hold the newline character (`"\n"'). If they did, migration of this
-string did not work because the string didn't obey the syntax rule for
-a string in `gawk'. `SUBSEP' is used as a temporary replacement. If
-the list of hosts to visit holds at least one more entry, the agent
-migrates to that place to go on working there. Otherwise, we replace
-the `SUBSEP's with a newline character in the resulting string, and
-report it to the originating host, whose name is stored in
-`MOBVAR["MyOrigin"]'.
+annoying circumstance is the fact that the elements of 'MOBVAR' cannot
+hold the newline character ('"\n"'). If they did, migration of this
+string did not work because the string didn't obey the syntax rule for a
+string in 'gawk'. 'SUBSEP' is used as a temporary replacement. If the
+list of hosts to visit holds at least one more entry, the agent migrates
+to that place to go on working there. Otherwise, we replace the
+'SUBSEP's with a newline character in the resulting string, and report
+it to the originating host, whose name is stored in
+'MOBVAR["MyOrigin"]'.
---------- Footnotes ----------
- (1) `http://www.research.ibm.com/massive/mobag.ps'
+ (1) <http://www.research.ibm.com/massive/mobag.ps>
File: gawkinet.info, Node: STOXPRED, Next: PROTBASE, Prev: MOBAGWHO, Up:
Some Applications and Techniques
@@ -2980,30 +2967,30 @@ File: gawkinet.info, Node: STOXPRED, Next: PROTBASE,
Prev: MOBAGWHO, Up: Som
3.9 STOXPRED: Stock Market Prediction As A Service
==================================================
- Far out in the uncharted backwaters of the unfashionable end of
- the Western Spiral arm of the Galaxy lies a small unregarded
- yellow sun.
+ Far out in the uncharted backwaters of the unfashionable end of the
+ Western Spiral arm of the Galaxy lies a small unregarded yellow
+ sun.
Orbiting this at a distance of roughly ninety-two million miles is
an utterly insignificant little blue-green planet whose
ape-descendent life forms are so amazingly primitive that they
still think digital watches are a pretty neat idea.
- This planet has -- or rather had -- a problem, which was this:
- most of the people living on it were unhappy for pretty much of
- the time. Many solutions were suggested for this problem, but
- most of these were largely concerned with the movements of small
- green pieces of paper, which is odd because it wasn't the small
- green pieces of paper that were unhappy.
- Douglas Adams, `The Hitch Hiker's Guide to the Galaxy'
+ This planet has -- or rather had -- a problem, which was this: most
+ of the people living on it were unhappy for pretty much of the
+ time. Many solutions were suggested for this problem, but most of
+ these were largely concerned with the movements of small green
+ pieces of paper, which is odd because it wasn't the small green
+ pieces of paper that were unhappy.
+ Douglas Adams, 'The Hitch Hiker's Guide to the Galaxy'
Valuable services on the Internet are usually _not_ implemented as
-mobile agents. There are much simpler ways of implementing services.
-All Unix systems provide, for example, the `cron' service. Unix system
+mobile agents. There are much simpler ways of implementing services.
+All Unix systems provide, for example, the 'cron' service. Unix system
users can write a list of tasks to be done each day, each week, twice a
-day, or just once. The list is entered into a file named `crontab'.
+day, or just once. The list is entered into a file named 'crontab'.
For example, to distribute a newsletter on a daily basis this way, use
-`cron' for calling a script each day early in the morning.
+'cron' for calling a script each day early in the morning.
# run at 8 am on weekdays, distribute the newsletter
0 8 * * 1-5 $HOME/bin/daily.job >> $HOME/log/newsletter 2>&1
@@ -3012,13 +2999,13 @@ For example, to distribute a newsletter on a daily
basis this way, use
assembles it in a nice form and sends the results via email to the
customers.
- The following is an example of a primitive newsletter on stock
-market prediction. It is a report which first tries to predict the
-change of each share in the Dow Jones Industrial Index for the
-particular day. Then it mentions some especially promising shares as
-well as some shares which look remarkably bad on that day. The report
-ends with the usual disclaimer which tells every child _not_ to try
-this at home and hurt anybody.
+ The following is an example of a primitive newsletter on stock market
+prediction. It is a report which first tries to predict the change of
+each share in the Dow Jones Industrial Index for the particular day.
+Then it mentions some especially promising shares as well as some shares
+which look remarkably bad on that day. The report ends with the usual
+disclaimer which tells every child _not_ to try this at home and hurt
+anybody.
Good morning Uncle Scrooge,
@@ -3053,7 +3040,7 @@ this at home and hurt anybody.
DD http://biz.yahoo.com/n/d/dd.html
...
- The script as a whole is rather long. In order to ease the pain of
+ The script as a whole is rather long. In order to ease the pain of
studying other people's source code, we have broken the script up into
meaningful parts which are invoked one after the other. The basic
structure of the script is as follows:
@@ -3068,17 +3055,17 @@ structure of the script is as follows:
}
The earlier parts store data into variables and arrays which are
-subsequently used by later parts of the script. The `Init' function
+subsequently used by later parts of the script. The 'Init' function
first checks if the script is invoked correctly (without any
-parameters). If not, it informs the user of the correct usage. What
-follows are preparations for the retrieval of the historical quote
-data. The names of the 30 stock shares are stored in an array `name'
-along with the current date in `day', `month', and `year'.
+parameters). If not, it informs the user of the correct usage. What
+follows are preparations for the retrieval of the historical quote data.
+The names of the 30 stock shares are stored in an array 'name' along
+with the current date in 'day', 'month', and 'year'.
All users who are separated from the Internet by a firewall and have
-to direct their Internet accesses to a proxy must supply the name of
-the proxy to this script with the `-v Proxy=NAME' option. For most
-users, the default proxy and port number should suffice.
+to direct their Internet accesses to a proxy must supply the name of the
+proxy to this script with the '-v Proxy=NAME' option. For most users,
+the default proxy and port number should suffice.
function Init() {
if (ARGC != 1) {
@@ -3102,12 +3089,12 @@ users, the default proxy and port number should suffice.
YahooData = "/inet/tcp/0/" Proxy "/" ProxyPort
}
- There are two really interesting parts in the script. One is the
+ There are two really interesting parts in the script. One is the
function which reads the historical stock quotes from an Internet
-server. The other is the one that does the actual prediction. In the
-following function we see how the quotes are read from the Yahoo
-server. The data which comes from the server is in CSV format
-(comma-separated values):
+server. The other is the one that does the actual prediction. In the
+following function we see how the quotes are read from the Yahoo server.
+The data which comes from the server is in CSV format (comma-separated
+values):
Date,Open,High,Low,Close,Volume
9-Oct-00,22.75,22.75,21.375,22.375,7888500
@@ -3116,22 +3103,22 @@ server. The data which comes from the server is in CSV
format
Lines contain values of the same time instant, whereas columns are
separated by commas and contain the kind of data that is described in
-the header (first) line. At first, `gawk' is instructed to separate
-columns by commas (`FS = ","'). In the loop that follows, a connection
+the header (first) line. At first, 'gawk' is instructed to separate
+columns by commas ('FS = ","'). In the loop that follows, a connection
to the Yahoo server is first opened, then a download takes place, and
-finally the connection is closed. All this happens once for each ticker
-symbol. In the body of this loop, an Internet address is built up as a
-string according to the rules of the Yahoo server. The starting and
-ending date are chosen to be exactly the same, but one year apart in
-the past. All the action is initiated within the `printf' command which
+finally the connection is closed. All this happens once for each ticker
+symbol. In the body of this loop, an Internet address is built up as a
+string according to the rules of the Yahoo server. The starting and
+ending date are chosen to be exactly the same, but one year apart in the
+past. All the action is initiated within the 'printf' command which
transmits the request for data to the Yahoo server.
In the inner loop, the server's data is first read and then scanned
-line by line. Only lines which have six columns and the name of a month
-in the first column contain relevant data. This data is stored in the
-two-dimensional array `quote'; one dimension being time, the other
-being the ticker symbol. During retrieval of the first stock's data,
-the calendar names of the time instances are stored in the array `day'
+line by line. Only lines which have six columns and the name of a month
+in the first column contain relevant data. This data is stored in the
+two-dimensional array 'quote'; one dimension being time, the other being
+the ticker symbol. During retrieval of the first stock's data, the
+calendar names of the time instances are stored in the array 'day'
because we need them later.
function ReadQuotes() {
@@ -3157,9 +3144,9 @@ because we need them later.
Now that we _have_ the data, it can be checked once again to make
sure that no individual stock is missing or invalid, and that all the
-stock quotes are aligned correctly. Furthermore, we renumber the time
-instances. The most recent day gets day number 1 and all other days get
-consecutive numbers. All quotes are rounded toward the nearest whole
+stock quotes are aligned correctly. Furthermore, we renumber the time
+instances. The most recent day gets day number 1 and all other days get
+consecutive numbers. All quotes are rounded toward the nearest whole
number in US Dollars.
function CleanUp() {
@@ -3181,13 +3168,13 @@ number in US Dollars.
Now we have arrived at the second really interesting part of the
whole affair. What we present here is a very primitive prediction
algorithm: _If a stock fell yesterday, assume it will also fall today;
-if it rose yesterday, assume it will rise today_. (Feel free to
-replace this algorithm with a smarter one.) If a stock changed in the
-same direction on two consecutive days, this is an indication which
-should be highlighted. Two-day advances are stored in `hot' and
-two-day declines in `avoid'.
+if it rose yesterday, assume it will rise today_. (Feel free to replace
+this algorithm with a smarter one.) If a stock changed in the same
+direction on two consecutive days, this is an indication which should be
+highlighted. Two-day advances are stored in 'hot' and two-day declines
+in 'avoid'.
- The rest of the function is a sanity check. It counts the number of
+ The rest of the function is a sanity check. It counts the number of
correct predictions in relation to the total number of predictions one
could have made in the year before.
@@ -3224,9 +3211,9 @@ could have made in the year before.
}
}
- At this point the hard work has been done: the array `predict'
-contains the predictions for all the ticker symbols. It is up to the
-function `Report' to find some nice words to introduce the desired
+ At this point the hard work has been done: the array 'predict'
+contains the predictions for all the ticker symbols. It is up to the
+function 'Report' to find some nice words to introduce the desired
information.
function Report() {
@@ -3263,8 +3250,8 @@ information.
report = report "you should visit a doctor who can treat your ailment."
}
- The function `SendMail' goes through the list of customers and opens
-a pipe to the `mail' command for each of them. Each one receives an
+ The function 'SendMail' goes through the list of customers and opens
+a pipe to the 'mail' command for each of them. Each one receives an
email message with a proper subject heading and is addressed with his
full name.
@@ -3290,8 +3277,8 @@ all the ticker symbols and sending the emails may take
several minutes
to complete, depending upon network traffic and the speed of the
available Internet link. The quality of the prediction algorithm is
likely to be disappointing. Try to find a better one. Should you find
-one with a success rate of more than 50%, please tell us about it! It
-is only for the sake of curiosity, of course. `:-)'
+one with a success rate of more than 50%, please tell us about it! It
+is only for the sake of curiosity, of course. ':-)'
File: gawkinet.info, Node: PROTBASE, Prev: STOXPRED, Up: Some Applications
and Techniques
@@ -3300,75 +3287,75 @@ File: gawkinet.info, Node: PROTBASE, Prev: STOXPRED,
Up: Some Applications an
===================================================
Hoare's Law of Large Problems: Inside every large problem is a
- small problem struggling to get out.
+ small problem struggling to get out.
Yahoo's database of stock market data is just one among the many
-large databases on the Internet. Another one is located at NCBI
-(National Center for Biotechnology Information). Established in 1988 as
+large databases on the Internet. Another one is located at NCBI
+(National Center for Biotechnology Information). Established in 1988 as
a national resource for molecular biology information, NCBI creates
public databases, conducts research in computational biology, develops
software tools for analyzing genome data, and disseminates biomedical
-information. In this section, we look at one of NCBI's public services,
+information. In this section, we look at one of NCBI's public services,
which is called BLAST (Basic Local Alignment Search Tool).
You probably know that the information necessary for reproducing
-living cells is encoded in the genetic material of the cells. The
-genetic material is a very long chain of four base nucleotides. It is
-the order of appearance (the sequence) of nucleotides which contains
-the information about the substance to be produced. Scientists in
+living cells is encoded in the genetic material of the cells. The
+genetic material is a very long chain of four base nucleotides. It is
+the order of appearance (the sequence) of nucleotides which contains the
+information about the substance to be produced. Scientists in
biotechnology often find a specific fragment, determine the nucleotide
-sequence, and need to know where the sequence at hand comes from. This
-is where the large databases enter the game. At NCBI, databases store
+sequence, and need to know where the sequence at hand comes from. This
+is where the large databases enter the game. At NCBI, databases store
the knowledge about which sequences have ever been found and where they
have been found. When the scientist sends his sequence to the BLAST
service, the server looks for regions of genetic material in its
database which look the most similar to the delivered nucleotide
-sequence. After a search time of some seconds or minutes the server
-sends an answer to the scientist. In order to make access simple, NCBI
+sequence. After a search time of some seconds or minutes the server
+sends an answer to the scientist. In order to make access simple, NCBI
chose to offer their database service through popular Internet
-protocols. There are four basic ways to use the so-called BLAST
+protocols. There are four basic ways to use the so-called BLAST
services:
- * The easiest way to use BLAST is through the web. Users may simply
+ * The easiest way to use BLAST is through the web. Users may simply
point their browsers at the NCBI home page and link to the BLAST
pages. NCBI provides a stable URL that may be used to perform
- BLAST searches without interactive use of a web browser. This is
+ BLAST searches without interactive use of a web browser. This is
what we will do later in this section. A demonstration client and
- a `README' file demonstrate how to access this URL.
+ a 'README' file demonstrate how to access this URL.
- * Currently, `blastcl3' is the standard network BLAST client. You
- can download `blastcl3' from the anonymous FTP location.
+ * Currently, 'blastcl3' is the standard network BLAST client. You
+ can download 'blastcl3' from the anonymous FTP location.
* BLAST 2.0 can be run locally as a full executable and can be used
to run BLAST searches against private local databases, or
- downloaded copies of the NCBI databases. BLAST 2.0 executables may
+ downloaded copies of the NCBI databases. BLAST 2.0 executables may
be found on the NCBI anonymous FTP server.
* The NCBI BLAST Email server is the best option for people without
- convenient access to the web. A similarity search can be performed
+ convenient access to the web. A similarity search can be performed
by sending a properly formatted mail message containing the
nucleotide or protein query sequence to <address@hidden>.
- The query sequence is compared against the specified database
- using the BLAST algorithm and the results are returned in an email
- message. For more information on formulating email BLAST searches,
+ The query sequence is compared against the specified database using
+ the BLAST algorithm and the results are returned in an email
+ message. For more information on formulating email BLAST searches,
you can send a message consisting of the word "HELP" to the same
address, <address@hidden>.
- Our starting point is the demonstration client mentioned in the
-first option. The `README' file that comes along with the client
-explains the whole process in a nutshell. In the rest of this section,
-we first show what such requests look like. Then we show how to use
-`gawk' to implement a client in about 10 lines of code. Finally, we
-show how to interpret the result returned from the service.
+ Our starting point is the demonstration client mentioned in the first
+option. The 'README' file that comes along with the client explains the
+whole process in a nutshell. In the rest of this section, we first show
+what such requests look like. Then we show how to use 'gawk' to
+implement a client in about 10 lines of code. Finally, we show how to
+interpret the result returned from the service.
Sequences are expected to be represented in the standard IUB/IUPAC
-amino acid and nucleic acid codes, with these exceptions: lower-case
+amino acid and nucleic acid codes, with these exceptions: lower-case
letters are accepted and are mapped into upper-case; a single hyphen or
dash can be used to represent a gap of indeterminate length; and in
-amino acid sequences, `U' and `*' are acceptable letters (see below).
+amino acid sequences, 'U' and '*' are acceptable letters (see below).
Before submitting a request, any numerical digits in the query sequence
should either be removed or replaced by appropriate letter codes (e.g.,
-`N' for unknown nucleic acid residue or `X' for unknown amino acid
+'N' for unknown nucleic acid residue or 'X' for unknown amino acid
residue). The nucleic acid codes supported are:
A --> adenosine M --> A C (amino)
@@ -3381,10 +3368,10 @@ residue). The nucleic acid codes supported are:
K --> G T (keto) N --> A G C T (any)
- gap of indeterminate length
- Now you know the alphabet of nucleotide sequences. The last two lines
-of the following example query show you such a sequence, which is
+ Now you know the alphabet of nucleotide sequences. The last two
+lines of the following example query show you such a sequence, which is
obviously made up only of elements of the alphabet just described.
-Store this example query into a file named `protbase.request'. You are
+Store this example query into a file named 'protbase.request'. You are
now ready to send it to the server with the demonstration client.
PROGRAM blastn
@@ -3396,38 +3383,38 @@ now ready to send it to the server with the
demonstration client.
caccaccatggacagcaaa
The actual search request begins with the mandatory parameter
-`PROGRAM' in the first column followed by the value `blastn' (the name
-of the program) for searching nucleic acids. The next line contains
-the mandatory search parameter `DATALIB' with the value `month' for the
+'PROGRAM' in the first column followed by the value 'blastn' (the name
+of the program) for searching nucleic acids. The next line contains the
+mandatory search parameter 'DATALIB' with the value 'month' for the
newest nucleic acid sequences. The third line contains an optional
-`EXPECT' parameter and the value desired for it. The fourth line
-contains the mandatory `BEGIN' directive, followed by the query
-sequence in FASTA/Pearson format. Each line of information must be
-less than 80 characters in length.
+'EXPECT' parameter and the value desired for it. The fourth line
+contains the mandatory 'BEGIN' directive, followed by the query sequence
+in FASTA/Pearson format. Each line of information must be less than 80
+characters in length.
The "month" database contains all new or revised sequences released
in the last 30 days and is useful for searching against new sequences.
-There are five different blast programs, `blastn' being the one that
-compares a nucleotide query sequence against a nucleotide sequence
+There are five different blast programs, 'blastn' being the one that
+compares a nucleotide query sequence against a nucleotide sequence
database.
The last server directive that must appear in every request is the
-`BEGIN' directive. The query sequence should immediately follow the
-`BEGIN' directive and must appear in FASTA/Pearson format. A sequence
+'BEGIN' directive. The query sequence should immediately follow the
+'BEGIN' directive and must appear in FASTA/Pearson format. A sequence
in FASTA/Pearson format begins with a single-line description. The
description line, which is required, is distinguished from the lines of
-sequence data that follow it by having a greater-than (`>') symbol in
-the first column. For the purposes of the BLAST server, the text of
-the description is arbitrary.
-
- If you prefer to use a client written in `gawk', just store the
-following 10 lines of code into a file named `protbase.awk' and use
-this client instead. Invoke it with `gawk -f protbase.awk
-protbase.request'. Then wait a minute and watch the result coming in.
-In order to replicate the demonstration client's behavior as closely as
-possible, this client does not use a proxy server. We could also have
-extended the client program in *note Retrieving Web Pages: GETURL, to
-implement the client request from `protbase.awk' as a special case.
+sequence data that follow it by having a greater-than ('>') symbol in
+the first column. For the purposes of the BLAST server, the text of the
+description is arbitrary.
+
+ If you prefer to use a client written in 'gawk', just store the
+following 10 lines of code into a file named 'protbase.awk' and use this
+client instead. Invoke it with 'gawk -f protbase.awk protbase.request'.
+Then wait a minute and watch the result coming in. In order to
+replicate the demonstration client's behavior as closely as possible,
+this client does not use a proxy server. We could also have extended
+the client program in *note Retrieving Web Pages: GETURL, to implement
+the client request from 'protbase.awk' as a special case.
{ request = request "\n" $0 }
@@ -3442,18 +3429,18 @@ implement the client request from `protbase.awk' as a
special case.
}
The demonstration client from NCBI is 214 lines long (written in C)
-and it is not immediately obvious what it does. Our client is so short
-that it _is_ obvious what it does. First it loops over all lines of the
-query and stores the whole query into a variable. Then the script
+and it is not immediately obvious what it does. Our client is so short
+that it _is_ obvious what it does. First it loops over all lines of the
+query and stores the whole query into a variable. Then the script
establishes an Internet connection to the NCBI server and transmits the
-query by framing it with a proper HTTP request. Finally it receives and
+query by framing it with a proper HTTP request. Finally it receives and
prints the complete result coming from the server.
- Now, let us look at the result. It begins with an HTTP header, which
-you can ignore. Then there are some comments about the query having been
-filtered to avoid spuriously high scores. After this, there is a
+ Now, let us look at the result. It begins with an HTTP header, which
+you can ignore. Then there are some comments about the query having
+been filtered to avoid spuriously high scores. After this, there is a
reference to the paper that describes the software being used for
-searching the data base. After a repetition of the original query's
+searching the data base. After a repetition of the original query's
description we find the list of significant alignments:
Sequences producing significant alignments: (bits)
Value
@@ -3469,13 +3456,13 @@ description we find the list of significant alignments:
This means that the query sequence was found in seven human
chromosomes. But the value 0.20 (20%) means that the probability of an
accidental match is rather high (20%) in all cases and should be taken
-into account. You may wonder what the first column means. It is a key
-to the specific database in which this occurrence was found. The
-unique sequence identifiers reported in the search results can be used
-as sequence retrieval keys via the NCBI server. The syntax of sequence
+into account. You may wonder what the first column means. It is a key
+to the specific database in which this occurrence was found. The unique
+sequence identifiers reported in the search results can be used as
+sequence retrieval keys via the NCBI server. The syntax of sequence
header lines used by the NCBI BLAST server depends on the database from
-which each sequence was obtained. The table below lists the
-identifiers for the databases from which the sequences were derived.
+which each sequence was obtained. The table below lists the identifiers
+for the databases from which the sequences were derived.
Database Name Identifier Syntax
============================ ========================
@@ -3490,14 +3477,14 @@ identifiers for the databases from which the sequences
were derived.
Patents pat|country|number
GenInfo Backbone Id bbs|number
- For example, an identifier might be `gb|AC021182.14|AC021182', where
-the `gb' tag indicates that the identifier refers to a GenBank sequence,
-`AC021182.14' is its GenBank ACCESSION, and `AC021182' is the GenBank
-LOCUS. The identifier contains no spaces, so that a space indicates
-the end of the identifier.
+ For example, an identifier might be 'gb|AC021182.14|AC021182', where
+the 'gb' tag indicates that the identifier refers to a GenBank sequence,
+'AC021182.14' is its GenBank ACCESSION, and 'AC021182' is the GenBank
+LOCUS. The identifier contains no spaces, so that a space indicates the
+end of the identifier.
- Let us continue in the result listing. Each of the seven alignments
-mentioned above is subsequently described in detail. We will have a
+ Let us continue in the result listing. Each of the seven alignments
+mentioned above is subsequently described in detail. We will have a
closer look at the first of them.
>gb|AC021182.14|AC021182 Homo sapiens chromosome 7 clone RP11-733N23,
WORKING DRAFT SEQUENCE, 4
@@ -3512,31 +3499,31 @@ closer look at the first of them.
|||||||||||||||||||
Sbjct: 69786 tggtgaagtgtgtttcttg 69804
- This alignment was located on the human chromosome 7. The fragment
-on which part of the query was found had a total length of 176383. Only
+ This alignment was located on the human chromosome 7. The fragment
+on which part of the query was found had a total length of 176383. Only
19 of the nucleotides matched and the matching sequence ran from
character 35 to 53 in the query sequence and from 69786 to 69804 in the
fragment on chromosome 7. If you are still reading at this point, you
are probably interested in finding out more about Computational Biology
and you might appreciate the following hints.
- 1. There is a book called `Introduction to Computational Biology' by
+ 1. There is a book called 'Introduction to Computational Biology' by
Michael S. Waterman, which is worth reading if you are seriously
- interested. You can find a good book review on the Internet.
+ interested. You can find a good book review on the Internet.
2. While Waterman's book can explain to you the algorithms employed
internally in the database search engines, most practitioners
- prefer to approach the subject differently. The applied side of
+ prefer to approach the subject differently. The applied side of
Computational Biology is called Bioinformatics, and emphasizes the
tools available for day-to-day work as well as how to actually
- _use_ them. One of the very few affordable books on Bioinformatics
- is `Developing Bioinformatics Computer Skills'.
+ _use_ them. One of the very few affordable books on Bioinformatics
+ is 'Developing Bioinformatics Computer Skills'.
3. The sequences _gawk_ and _gnuawk_ are in widespread use in the
- genetic material of virtually every earthly living being. Let us
+ genetic material of virtually every earthly living being. Let us
take this as a clear indication that the divine creator has
- intended `gawk' to prevail over other scripting languages such as
- `perl', `tcl', or `python' which are not even proper sequences.
+ intended 'gawk' to prevail over other scripting languages such as
+ 'perl', 'tcl', or 'python' which are not even proper sequences.
(:-)
@@ -3548,123 +3535,122 @@ File: gawkinet.info, Node: Links, Next: GNU Free
Documentation License, Prev:
This section lists the URLs for various items discussed in this major
node. They are presented in the order in which they appear.
-`Internet Programming with Python'
- `http://www.fsbassociates.com/books/python.htm'
+'Internet Programming with Python'
+ <http://www.fsbassociates.com/books/python.htm>
-`Advanced Perl Programming'
- `http://www.oreilly.com/catalog/advperl'
+'Advanced Perl Programming'
+ <http://www.oreilly.com/catalog/advperl>
-`Web Client Programming with Perl'
- `http://www.oreilly.com/catalog/webclient'
+'Web Client Programming with Perl'
+ <http://www.oreilly.com/catalog/webclient>
Richard Stevens's home page and book
- `http://www.kohala.com/~rstevens'
+ <http://www.kohala.com/~rstevens>
The SPAK home page
-
`http://www.userfriendly.net/linux/RPM/contrib/libc6/i386/spak-0.6b-1.i386.html'
+
<http://www.userfriendly.net/linux/RPM/contrib/libc6/i386/spak-0.6b-1.i386.html>
-Volume III of `Internetworking with TCP/IP', by Comer and Stevens
- `http://www.cs.purdue.edu/homes/dec/tcpip3s.cont.html'
+Volume III of 'Internetworking with TCP/IP', by Comer and Stevens
+ <http://www.cs.purdue.edu/homes/dec/tcpip3s.cont.html>
XBM Graphics File Format
- `http://www.wotsit.org/download.asp?f=xbm'
+ <http://www.wotsit.org/download.asp?f=xbm>
GNUPlot
- `http://www.cs.dartmouth.edu/gnuplot_info.html'
+ <http://www.cs.dartmouth.edu/gnuplot_info.html>
Mark Humphrys' Eliza page
- `http://www.compapp.dcu.ie/~humphrys/eliza.html'
+ <http://www.compapp.dcu.ie/~humphrys/eliza.html>
Yahoo! Eliza Information
-
`http://dir.yahoo.com/Recreation/Games/Computer_Games/Internet_Games/Web_Games/Artificial_Intelligence'
+
<http://dir.yahoo.com/Recreation/Games/Computer_Games/Internet_Games/Web_Games/Artificial_Intelligence>
Java versions of Eliza
- `http://www.tjhsst.edu/Psych/ch1/eliza.html'
+ <http://www.tjhsst.edu/Psych/ch1/eliza.html>
Java versions of Eliza with source code
- `http://home.adelphia.net/~lifeisgood/eliza/eliza.htm'
+ <http://home.adelphia.net/~lifeisgood/eliza/eliza.htm>
Eliza Programs with Explanations
- `http://chayden.net/chayden/eliza/Eliza.shtml'
+ <http://chayden.net/chayden/eliza/Eliza.shtml>
Loebner Contest
- `http://acm.org/~loebner/loebner-prize.htmlx'
+ <http://acm.org/~loebner/loebner-prize.htmlx>
Tck/Tk Information
- `http://www.scriptics.com/'
+ <http://www.scriptics.com/>
Intel 80x86 Processors
- `http://developer.intel.com/design/platform/embedpc/what_is.htm'
+ <http://developer.intel.com/design/platform/embedpc/what_is.htm>
AMD Elan Processors
-
`http://www.amd.com/products/epd/processors/4.32bitcont/32bitcont/index.html'
+
<http://www.amd.com/products/epd/processors/4.32bitcont/32bitcont/index.html>
XINU
- `http://willow.canberra.edu.au/~chrisc/xinu.html'
+ <http://willow.canberra.edu.au/~chrisc/xinu.html>
GNU/Linux
- `http://uclinux.lineo.com/'
+ <http://uclinux.lineo.com/>
Embedded PCs
-
`http://dir.yahoo.com/Business_and_Economy/Business_to_Business/Computers/Hardware/Embedded_Control/'
+
<http://dir.yahoo.com/Business_and_Economy/Business_to_Business/Computers/Hardware/Embedded_Control/>
MiniSQL
- `http://www.hughes.com.au/library/'
+ <http://www.hughes.com.au/library/>
Market Share Surveys
- `http://www.netcraft.com/survey'
+ <http://www.netcraft.com/survey>
-`Numerical Recipes in C: The Art of Scientific Computing'
- `http://www.nr.com'
+'Numerical Recipes in C: The Art of Scientific Computing'
+ <http://www.nr.com>
VRML
- `http://www.vrml.org'
+ <http://www.vrml.org>
The VRML FAQ
- `http://www.vrml.org/technicalinfo/specifications/specifications.htm#FAQ'
+ <http://www.vrml.org/technicalinfo/specifications/specifications.htm#FAQ>
The UMBC Agent Web
- `http://www.cs.umbc.edu/agents'
+ <http://www.cs.umbc.edu/agents>
Apache Web Server
- `http://www.apache.org'
+ <http://www.apache.org>
National Center for Biotechnology Information (NCBI)
- `http://www.ncbi.nlm.nih.gov'
+ <http://www.ncbi.nlm.nih.gov>
Basic Local Alignment Search Tool (BLAST)
- `http://www.ncbi.nlm.nih.gov/BLAST/blast_overview.html'
+ <http://www.ncbi.nlm.nih.gov/BLAST/blast_overview.html>
NCBI Home Page
- `http://www.ncbi.nlm.nih.gov'
+ <http://www.ncbi.nlm.nih.gov>
BLAST Pages
- `http://www.ncbi.nlm.nih.gov/BLAST'
+ <http://www.ncbi.nlm.nih.gov/BLAST>
BLAST Demonstration Client
- `ftp://ncbi.nlm.nih.gov/blast/blasturl/'
+ <ftp://ncbi.nlm.nih.gov/blast/blasturl/>
BLAST anonymous FTP location
- `ftp://ncbi.nlm.nih.gov/blast/network/netblast/'
+ <ftp://ncbi.nlm.nih.gov/blast/network/netblast/>
BLAST 2.0 Executables
- `ftp://ncbi.nlm.nih.gov/blast/executables/'
+ <ftp://ncbi.nlm.nih.gov/blast/executables/>
IUB/IUPAC Amino Acid and Nucleic Acid Codes
- `http://www.uthscsa.edu/geninfo/blastmail.html#item6'
+ <http://www.uthscsa.edu/geninfo/blastmail.html#item6>
FASTA/Pearson Format
- `http://www.ncbi.nlm.nih.gov/BLAST/fasta.html'
+ <http://www.ncbi.nlm.nih.gov/BLAST/fasta.html>
Fasta/Pearson Sequence in Java
- `http://www.kazusa.or.jp/java/codon_table_java/'
-
-Book Review of `Introduction to Computational Biology'
- `http://www.acm.org/crossroads/xrds5-1/introcb.html'
+ <http://www.kazusa.or.jp/java/codon_table_java/>
-`Developing Bioinformatics Computer Skills'
- `http://www.oreilly.com/catalog/bioskills/'
+Book Review of 'Introduction to Computational Biology'
+ <http://www.acm.org/crossroads/xrds5-1/introcb.html>
+'Developing Bioinformatics Computer Skills'
+ <http://www.oreilly.com/catalog/bioskills/>
File: gawkinet.info, Node: GNU Free Documentation License, Next: Index,
Prev: Links, Up: Top
@@ -3675,7 +3661,7 @@ GNU Free Documentation License
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
- `http://fsf.org/'
+ <http://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
@@ -3700,21 +3686,21 @@ GNU Free Documentation License
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
- of subject matter or whether it is published as a printed book.
- We recommend this License principally for works whose purpose is
+ of subject matter or whether it is published as a printed book. We
+ recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
- that contains a notice placed by the copyright holder saying it
- can be distributed under the terms of this License. Such a notice
+ that contains a notice placed by the copyright holder saying it can
+ be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
- of the public is a licensee, and is addressed as "you". You
- accept the license if you copy, modify or distribute the work in a
- way requiring permission under copyright law.
+ of the public is a licensee, and is addressed as "you". You accept
+ the license if you copy, modify or distribute the work in a way
+ requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
@@ -3732,12 +3718,12 @@ GNU Free Documentation License
regarding them.
The "Invariant Sections" are certain Secondary Sections whose
- titles are designated, as being those of Invariant Sections, in
- the notice that says that the Document is released under this
- License. If a section does not fit the above definition of
- Secondary then it is not allowed to be designated as Invariant.
- The Document may contain zero Invariant Sections. If the Document
- does not identify any Invariant Sections then there are none.
+ titles are designated, as being those of Invariant Sections, in the
+ notice that says that the Document is released under this License.
+ If a section does not fit the above definition of Secondary then it
+ is not allowed to be designated as Invariant. The Document may
+ contain zero Invariant Sections. If the Document does not identify
+ any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
@@ -3748,27 +3734,27 @@ GNU Free Documentation License
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
- straightforwardly with generic text editors or (for images
- composed of pixels) generic paint programs or (for drawings) some
- widely available drawing editor, and that is suitable for input to
- text formatters or for automatic translation to a variety of
- formats suitable for input to text formatters. A copy made in an
- otherwise Transparent file format whose markup, or absence of
- markup, has been arranged to thwart or discourage subsequent
- modification by readers is not Transparent. An image format is
- not Transparent if used for any substantial amount of text. A
- copy that is not "Transparent" is called "Opaque".
+ straightforwardly with generic text editors or (for images composed
+ of pixels) generic paint programs or (for drawings) some widely
+ available drawing editor, and that is suitable for input to text
+ formatters or for automatic translation to a variety of formats
+ suitable for input to text formatters. A copy made in an otherwise
+ Transparent file format whose markup, or absence of markup, has
+ been arranged to thwart or discourage subsequent modification by
+ readers is not Transparent. An image format is not Transparent if
+ used for any substantial amount of text. A copy that is not
+ "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
- SGML or XML using a publicly available DTD, and
- standard-conforming simple HTML, PostScript or PDF designed for
- human modification. Examples of transparent image formats include
- PNG, XCF and JPG. Opaque formats include proprietary formats that
- can be read and edited only by proprietary word processors, SGML or
- XML for which the DTD and/or processing tools are not generally
- available, and the machine-generated HTML, PostScript or PDF
- produced by some word processors for output purposes only.
+ SGML or XML using a publicly available DTD, and standard-conforming
+ simple HTML, PostScript or PDF designed for human modification.
+ Examples of transparent image formats include PNG, XCF and JPG.
+ Opaque formats include proprietary formats that can be read and
+ edited only by proprietary word processors, SGML or XML for which
+ the DTD and/or processing tools are not generally available, and
+ the machine-generated HTML, PostScript or PDF produced by some word
+ processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
@@ -3806,8 +3792,8 @@ GNU Free Documentation License
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
- distribute a large enough number of copies you must also follow
- the conditions in section 3.
+ distribute a large enough number of copies you must also follow the
+ conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
@@ -3821,12 +3807,11 @@ GNU Free Documentation License
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
- front cover must present the full title with all words of the
- title equally prominent and visible. You may add other material
- on the covers in addition. Copying with changes limited to the
- covers, as long as they preserve the title of the Document and
- satisfy these conditions, can be treated as verbatim copying in
- other respects.
+ front cover must present the full title with all words of the title
+ equally prominent and visible. You may add other material on the
+ covers in addition. Copying with changes limited to the covers, as
+ long as they preserve the title of the Document and satisfy these
+ conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
@@ -3834,40 +3819,39 @@ GNU Free Documentation License
adjacent pages.
If you publish or distribute Opaque copies of the Document
- numbering more than 100, you must either include a
- machine-readable Transparent copy along with each Opaque copy, or
- state in or with each Opaque copy a computer-network location from
- which the general network-using public has access to download
- using public-standard network protocols a complete Transparent
- copy of the Document, free of added material. If you use the
- latter option, you must take reasonably prudent steps, when you
- begin distribution of Opaque copies in quantity, to ensure that
- this Transparent copy will remain thus accessible at the stated
- location until at least one year after the last time you
- distribute an Opaque copy (directly or through your agents or
- retailers) of that edition to the public.
+ numbering more than 100, you must either include a machine-readable
+ Transparent copy along with each Opaque copy, or state in or with
+ each Opaque copy a computer-network location from which the general
+ network-using public has access to download using public-standard
+ network protocols a complete Transparent copy of the Document, free
+ of added material. If you use the latter option, you must take
+ reasonably prudent steps, when you begin distribution of Opaque
+ copies in quantity, to ensure that this Transparent copy will
+ remain thus accessible at the stated location until at least one
+ year after the last time you distribute an Opaque copy (directly or
+ through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
- the Document well before redistributing any large number of
- copies, to give them a chance to provide you with an updated
- version of the Document.
+ the Document well before redistributing any large number of copies,
+ to give them a chance to provide you with an updated version of the
+ Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
- release the Modified Version under precisely this License, with
- the Modified Version filling the role of the Document, thus
- licensing distribution and modification of the Modified Version to
- whoever possesses a copy of it. In addition, you must do these
- things in the Modified Version:
+ release the Modified Version under precisely this License, with the
+ Modified Version filling the role of the Document, thus licensing
+ distribution and modification of the Modified Version to whoever
+ possesses a copy of it. In addition, you must do these things in
+ the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
- distinct from that of the Document, and from those of
- previous versions (which should, if there were any, be listed
- in the History section of the Document). You may use the
- same title as a previous version if the original publisher of
- that version gives permission.
+ distinct from that of the Document, and from those of previous
+ versions (which should, if there were any, be listed in the
+ History section of the Document). You may use the same title
+ as a previous version if the original publisher of that
+ version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
@@ -3897,31 +3881,30 @@ GNU Free Documentation License
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
- authors, and publisher of the Modified Version as given on
- the Title Page. If there is no section Entitled "History" in
- the Document, create one stating the title, year, authors,
- and publisher of the Document as given on its Title Page,
- then add an item describing the Modified Version as stated in
- the previous sentence.
+ authors, and publisher of the Modified Version as given on the
+ Title Page. If there is no section Entitled "History" in the
+ Document, create one stating the title, year, authors, and
+ publisher of the Document as given on its Title Page, then add
+ an item describing the Modified Version as stated in the
+ previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
- previous versions it was based on. These may be placed in
- the "History" section. You may omit a network location for a
- work that was published at least four years before the
- Document itself, or if the original publisher of the version
- it refers to gives permission.
+ previous versions it was based on. These may be placed in the
+ "History" section. You may omit a network location for a work
+ that was published at least four years before the Document
+ itself, or if the original publisher of the version it refers
+ to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
- Preserve the Title of the section, and preserve in the
- section all the substance and tone of each of the contributor
+ Preserve the Title of the section, and preserve in the section
+ all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
- L. Preserve all the Invariant Sections of the Document,
- unaltered in their text and in their titles. Section numbers
- or the equivalent are not considered part of the section
- titles.
+ L. Preserve all the Invariant Sections of the Document, unaltered
+ in their text and in their titles. Section numbers or the
+ equivalent are not considered part of the section titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
@@ -3934,11 +3917,11 @@ GNU Free Documentation License
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
- material copied from the Document, you may at your option
- designate some or all of these sections as invariant. To do this,
- add their titles to the list of Invariant Sections in the Modified
- Version's license notice. These titles must be distinct from any
- other section titles.
+ material copied from the Document, you may at your option designate
+ some or all of these sections as invariant. To do this, add their
+ titles to the list of Invariant Sections in the Modified Version's
+ license notice. These titles must be distinct from any other
+ section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
@@ -3947,15 +3930,15 @@ GNU Free Documentation License
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
- and a passage of up to 25 words as a Back-Cover Text, to the end
- of the list of Cover Texts in the Modified Version. Only one
- passage of Front-Cover Text and one of Back-Cover Text may be
- added by (or through arrangements made by) any one entity. If the
- Document already includes a cover text for the same cover,
- previously added by you or by arrangement made by the same entity
- you are acting on behalf of, you may not add another; but you may
- replace the old one, on explicit permission from the previous
- publisher that added the old one.
+ and a passage of up to 25 words as a Back-Cover Text, to the end of
+ the list of Cover Texts in the Modified Version. Only one passage
+ of Front-Cover Text and one of Back-Cover Text may be added by (or
+ through arrangements made by) any one entity. If the Document
+ already includes a cover text for the same cover, previously added
+ by you or by arrangement made by the same entity you are acting on
+ behalf of, you may not add another; but you may replace the old
+ one, on explicit permission from the previous publisher that added
+ the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
@@ -3965,8 +3948,8 @@ GNU Free Documentation License
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
- modified versions, provided that you include in the combination
- all of the Invariant Sections of all of the original documents,
+ modified versions, provided that you include in the combination all
+ of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
@@ -3993,20 +3976,20 @@ GNU Free Documentation License
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
- rules of this License for verbatim copying of each of the
- documents in all other respects.
+ rules of this License for verbatim copying of each of the documents
+ in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
- a copy of this License into the extracted document, and follow
- this License in all other respects regarding verbatim copying of
- that document.
+ a copy of this License into the extracted document, and follow this
+ License in all other respects regarding verbatim copying of that
+ document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
- separate and independent documents or works, in or on a volume of
- a storage or distribution medium, is called an "aggregate" if the
+ separate and independent documents or works, in or on a volume of a
+ storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
@@ -4051,8 +4034,8 @@ GNU Free Documentation License
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
- provisionally, unless and until the copyright holder explicitly
- and finally terminates your license, and (b) permanently, if the
+ provisionally, unless and until the copyright holder explicitly and
+ finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
@@ -4064,33 +4047,33 @@ GNU Free Documentation License
after your receipt of the notice.
Termination of your rights under this section does not terminate
- the licenses of parties who have received copies or rights from
- you under this License. If your rights have been terminated and
- not permanently reinstated, receipt of a copy of some or all of
- the same material does not give you any rights to use it.
+ the licenses of parties who have received copies or rights from you
+ under this License. If your rights have been terminated and not
+ permanently reinstated, receipt of a copy of some or all of the
+ same material does not give you any rights to use it.
- 10. FUTURE REVISIONS OF THIS LICENSE
+ 10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
- `http://www.gnu.org/copyleft/'.
+ <http://www.gnu.org/copyleft/>.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
- published (not as a draft) by the Free Software Foundation. If
- the Document does not specify a version number of this License,
- you may choose any version ever published (not as a draft) by the
- Free Software Foundation. If the Document specifies that a proxy
- can decide which future versions of this License can be used, that
+ published (not as a draft) by the Free Software Foundation. If the
+ Document does not specify a version number of this License, you may
+ choose any version ever published (not as a draft) by the Free
+ Software Foundation. If the Document specifies that a proxy can
+ decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
- 11. RELICENSING
+ 11. RELICENSING
"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
@@ -4120,7 +4103,6 @@ GNU Free Documentation License
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
-
ADDENDUM: How to use this License for your documents
====================================================
@@ -4137,7 +4119,7 @@ notices just after the title page:
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
-Texts, replace the "with...Texts." line with this:
+Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
@@ -4148,9 +4130,9 @@ combination of the three, merge those two alternatives to
suit the
situation.
If your document contains nontrivial examples of program code, we
-recommend releasing these examples in parallel under your choice of
-free software license, such as the GNU General Public License, to
-permit their use in free software.
+recommend releasing these examples in parallel under your choice of free
+software license, such as the GNU General Public License, to permit
+their use in free software.
File: gawkinet.info, Node: Index, Prev: GNU Free Documentation License, Up:
Top
@@ -4161,152 +4143,156 @@ Index
[index ]
* Menu:
-* /inet/ files (gawk): Gawk Special Files. (line 34)
-* /inet/tcp special files (gawk): File /inet/tcp. (line 6)
-* /inet/udp special files (gawk): File /inet/udp. (line 6)
+* '/inet/' files ('gawk'): Gawk Special Files. (line 34)
+* '/inet/tcp' special files ('gawk'): File /inet/tcp. (line 6)
+* '/inet/udp' special files ('gawk'): File /inet/udp. (line 6)
+* '|' (vertical bar), '|&' operator (I/O): TCP Connecting. (line 25)
* advanced features, network connections: Troubleshooting. (line 6)
+* agent: Challenges. (line 75)
* agent <1>: MOBAGWHO. (line 6)
-* agent: Challenges. (line 76)
-* AI: Challenges. (line 76)
-* apache <1>: MOBAGWHO. (line 42)
+* AI: Challenges. (line 75)
* apache: WEBGRAB. (line 72)
+* apache <1>: MOBAGWHO. (line 42)
* Bioinformatics: PROTBASE. (line 227)
* BLAST, Basic Local Alignment Search Tool: PROTBASE. (line 6)
* blocking: Making Connections. (line 35)
* Boutell, Thomas: STATIST. (line 6)
* CGI (Common Gateway Interface): MOBAGWHO. (line 42)
* CGI (Common Gateway Interface), dynamic web pages and: Web page.
- (line 46)
+ (line 45)
* CGI (Common Gateway Interface), library: CGI Lib. (line 11)
* clients: Making Connections. (line 21)
-* Clinton, Bill: Challenges. (line 59)
-* Common Gateway Interface, See CGI: Web page. (line 46)
+* Clinton, Bill: Challenges. (line 58)
+* Common Gateway Interface, See CGI: Web page. (line 45)
* Computational Biology: PROTBASE. (line 227)
* contest: Challenges. (line 6)
-* cron utility: STOXPRED. (line 23)
+* 'cron' utility: STOXPRED. (line 23)
* CSV format: STOXPRED. (line 128)
* Dow Jones Industrial Index: STOXPRED. (line 44)
* ELIZA program: Simple Server. (line 11)
+* ELIZA program <1>: Simple Server. (line 178)
* email: Email. (line 11)
* FASTA/Pearson format: PROTBASE. (line 102)
* FDL (Free Documentation License): GNU Free Documentation License.
(line 6)
* filenames, for network access: Gawk Special Files. (line 29)
-* files, /inet/ (gawk): Gawk Special Files. (line 34)
-* files, /inet/tcp (gawk): File /inet/tcp. (line 6)
-* files, /inet/udp (gawk): File /inet/udp. (line 6)
-* finger utility: Setting Up. (line 22)
+* files, '/inet/' ('gawk'): Gawk Special Files. (line 34)
+* files, '/inet/tcp' ('gawk'): File /inet/tcp. (line 6)
+* files, '/inet/udp' ('gawk'): File /inet/udp. (line 6)
+* 'finger' utility: Setting Up. (line 22)
* Free Documentation License (FDL): GNU Free Documentation License.
(line 6)
* FTP (File Transfer Protocol): Basic Protocols. (line 45)
-* gawk, networking: Using Networking. (line 6)
-* gawk, networking, connections <1>: TCP Connecting. (line 6)
-* gawk, networking, connections: Special File Fields. (line 53)
-* gawk, networking, filenames: Gawk Special Files. (line 29)
-* gawk, networking, See Also email: Email. (line 6)
-* gawk, networking, service, establishing: Setting Up. (line 6)
-* gawk, networking, troubleshooting: Caveats. (line 6)
-* gawk, web and, See web service: Interacting Service. (line 6)
-* getline command: TCP Connecting. (line 11)
+* 'gawk', networking: Using Networking. (line 6)
+* 'gawk', networking, connections: Special File Fields. (line 53)
+* 'gawk', networking, connections <1>: TCP Connecting. (line 6)
+* 'gawk', networking, filenames: Gawk Special Files. (line 29)
+* 'gawk', networking, See Also email: Email. (line 6)
+* 'gawk', networking, service, establishing: Setting Up. (line 6)
+* 'gawk', networking, troubleshooting: Caveats. (line 6)
+* 'gawk', web and, See web service: Interacting Service. (line 6)
+* 'getline' command: TCP Connecting. (line 11)
* GETURL program: GETURL. (line 6)
+* GIF image format: Web page. (line 45)
* GIF image format <1>: STATIST. (line 6)
-* GIF image format: Web page. (line 46)
* GNU Free Documentation License: GNU Free Documentation License.
(line 6)
-* GNU/Linux <1>: REMCONF. (line 6)
-* GNU/Linux <2>: Interacting. (line 27)
* GNU/Linux: Troubleshooting. (line 54)
-* GNUPlot utility <1>: STATIST. (line 6)
+* GNU/Linux <1>: Interacting. (line 27)
+* GNU/Linux <2>: REMCONF. (line 6)
* GNUPlot utility: Interacting Service. (line 189)
-* Hoare, C.A.R. <1>: PROTBASE. (line 6)
+* GNUPlot utility <1>: STATIST. (line 6)
* Hoare, C.A.R.: MOBAGWHO. (line 6)
+* Hoare, C.A.R. <1>: PROTBASE. (line 6)
* hostname field: Special File Fields. (line 34)
-* HTML (Hypertext Markup Language): Web page. (line 30)
-* HTTP (Hypertext Transfer Protocol) <1>: Web page. (line 6)
+* HTML (Hypertext Markup Language): Web page. (line 29)
* HTTP (Hypertext Transfer Protocol): Basic Protocols. (line 45)
+* HTTP (Hypertext Transfer Protocol) <1>: Web page. (line 6)
* HTTP (Hypertext Transfer Protocol), record separators and: Web page.
- (line 30)
+ (line 29)
* HTTP server, core logic: Interacting Service. (line 6)
-* Humphrys, Mark: Simple Server. (line 179)
-* Hypertext Markup Language (HTML): Web page. (line 30)
+* HTTP server, core logic <1>: Interacting Service. (line 24)
+* Humphrys, Mark: Simple Server. (line 178)
+* Hypertext Markup Language (HTML): Web page. (line 29)
* Hypertext Transfer Protocol, See HTTP: Web page. (line 6)
* image format: STATIST. (line 6)
* images, in web pages: Interacting Service. (line 189)
-* images, retrieving over networks: Web page. (line 46)
-* input/output, two-way, See Also gawk, networking: Gawk Special Files.
+* images, retrieving over networks: Web page. (line 45)
+* input/output, two-way, See Also 'gawk', networking: Gawk Special Files.
(line 19)
* Internet, See networks: Interacting. (line 48)
* JavaScript: STATIST. (line 56)
-* Linux <1>: REMCONF. (line 6)
-* Linux <2>: Interacting. (line 27)
* Linux: Troubleshooting. (line 54)
+* Linux <1>: Interacting. (line 27)
+* Linux <2>: REMCONF. (line 6)
* Lisp: MOBAGWHO. (line 98)
* localport field: Gawk Special Files. (line 34)
* Loebner, Hugh: Challenges. (line 6)
-* Loui, Ronald: Challenges. (line 76)
+* Loui, Ronald: Challenges. (line 75)
* MAZE: MAZE. (line 6)
* Microsoft Windows: WEBGRAB. (line 43)
* Microsoft Windows, networking: Troubleshooting. (line 54)
* Microsoft Windows, networking, ports: Setting Up. (line 37)
-* MiniSQL: REMCONF. (line 111)
+* MiniSQL: REMCONF. (line 109)
* MOBAGWHO program: MOBAGWHO. (line 6)
* NCBI, National Center for Biotechnology Information: PROTBASE.
(line 6)
* network type field: Special File Fields. (line 11)
-* networks, gawk and: Using Networking. (line 6)
-* networks, gawk and, connections <1>: TCP Connecting. (line 6)
-* networks, gawk and, connections: Special File Fields. (line 53)
-* networks, gawk and, filenames: Gawk Special Files. (line 29)
-* networks, gawk and, See Also email: Email. (line 6)
-* networks, gawk and, service, establishing: Setting Up. (line 6)
-* networks, gawk and, troubleshooting: Caveats. (line 6)
+* networks, 'gawk' and: Using Networking. (line 6)
+* networks, 'gawk' and, connections: Special File Fields. (line 53)
+* networks, 'gawk' and, connections <1>: TCP Connecting. (line 6)
+* networks, 'gawk' and, filenames: Gawk Special Files. (line 29)
+* networks, 'gawk' and, See Also email: Email. (line 6)
+* networks, 'gawk' and, service, establishing: Setting Up. (line 6)
+* networks, 'gawk' and, troubleshooting: Caveats. (line 6)
* networks, ports, reserved: Setting Up. (line 37)
* networks, ports, specifying: Special File Fields. (line 24)
* networks, See Also web pages: PANIC. (line 6)
* Numerical Recipes: STATIST. (line 24)
-* ORS variable, HTTP and: Web page. (line 30)
-* ORS variable, POP and: Email. (line 36)
+* 'ORS' variable, HTTP and: Web page. (line 29)
+* 'ORS' variable, POP and: Email. (line 36)
* PANIC program: PANIC. (line 6)
* Perl: Using Networking. (line 14)
-* Perl, gawk networking and: Using Networking. (line 24)
+* Perl, 'gawk' networking and: Using Networking. (line 24)
* Perlis, Alan: MAZE. (line 6)
* pipes, networking and: TCP Connecting. (line 30)
+* PNG image format: Web page. (line 45)
* PNG image format <1>: STATIST. (line 6)
-* PNG image format: Web page. (line 46)
* POP (Post Office Protocol): Email. (line 6)
+* POP (Post Office Protocol) <1>: Email. (line 36)
* Post Office Protocol (POP): Email. (line 6)
* PostScript: STATIST. (line 138)
-* PROLOG: Challenges. (line 76)
+* PROLOG: Challenges. (line 75)
* PROTBASE: PROTBASE. (line 6)
* protocol field: Special File Fields. (line 17)
* PS image format: STATIST. (line 6)
* Python: Using Networking. (line 14)
-* Python, gawk networking and: Using Networking. (line 24)
-* record separators, HTTP and: Web page. (line 30)
+* Python, 'gawk' networking and: Using Networking. (line 24)
+* record separators, HTTP and: Web page. (line 29)
* record separators, POP and: Email. (line 36)
* REMCONF program: REMCONF. (line 6)
* remoteport field: Gawk Special Files. (line 34)
+* robot: Challenges. (line 84)
* robot <1>: WEBGRAB. (line 6)
-* robot: Challenges. (line 85)
-* RS variable, HTTP and: Web page. (line 30)
-* RS variable, POP and: Email. (line 36)
-* servers <1>: Setting Up. (line 22)
+* 'RS' variable, HTTP and: Web page. (line 29)
+* 'RS' variable, POP and: Email. (line 36)
* servers: Making Connections. (line 14)
+* servers <1>: Setting Up. (line 22)
* servers, as hosts: Special File Fields. (line 34)
* servers, HTTP: Interacting Service. (line 6)
* servers, web: Simple Server. (line 6)
* Simple Mail Transfer Protocol (SMTP): Email. (line 6)
-* SMTP (Simple Mail Transfer Protocol) <1>: Email. (line 6)
* SMTP (Simple Mail Transfer Protocol): Basic Protocols. (line 45)
+* SMTP (Simple Mail Transfer Protocol) <1>: Email. (line 6)
* STATIST program: STATIST. (line 6)
* STOXPRED program: STOXPRED. (line 6)
* synchronous communications: Making Connections. (line 35)
* Tcl/Tk: Using Networking. (line 14)
-* Tcl/Tk, gawk and <1>: Some Applications and Techniques.
+* Tcl/Tk, 'gawk' and: Using Networking. (line 24)
+* Tcl/Tk, 'gawk' and <1>: Some Applications and Techniques.
(line 22)
-* Tcl/Tk, gawk and: Using Networking. (line 24)
-* TCP (Transmission Control Protocol) <1>: File /inet/tcp. (line 6)
* TCP (Transmission Control Protocol): Using Networking. (line 29)
+* TCP (Transmission Control Protocol) <1>: File /inet/tcp. (line 6)
* TCP (Transmission Control Protocol), connection, establishing: TCP
Connecting.
(line 6)
* TCP (Transmission Control Protocol), UDP and: Interacting. (line 48)
@@ -4314,7 +4300,7 @@ Index
* TCP/IP, protocols, selecting: Special File Fields. (line 17)
* TCP/IP, sockets and: Gawk Special Files. (line 19)
* Transmission Control Protocol, See TCP: Using Networking. (line 29)
-* troubleshooting, gawk, networks: Caveats. (line 6)
+* troubleshooting, 'gawk', networks: Caveats. (line 6)
* troubleshooting, networks, connections: Troubleshooting. (line 6)
* troubleshooting, networks, timeouts: Caveats. (line 18)
* UDP (User Datagram Protocol): File /inet/udp. (line 6)
@@ -4322,76 +4308,75 @@ Index
* Unix, network ports and: Setting Up. (line 37)
* URLCHK program: URLCHK. (line 6)
* User Datagram Protocol, See UDP: File /inet/udp. (line 6)
-* vertical bar (|), |& operator (I/O): TCP Connecting. (line 25)
+* vertical bar ('|'), '|&' operator (I/O): TCP Connecting. (line 25)
* VRML: MAZE. (line 6)
* web browsers, See web service: Interacting Service. (line 6)
* web pages: Web page. (line 6)
* web pages, images in: Interacting Service. (line 189)
* web pages, retrieving: GETURL. (line 6)
* web servers: Simple Server. (line 6)
-* web service <1>: PANIC. (line 6)
* web service: Primitive Service. (line 6)
+* web service <1>: PANIC. (line 6)
* WEBGRAB program: WEBGRAB. (line 6)
* Weizenbaum, Joseph: Simple Server. (line 11)
* XBM image format: Interacting Service. (line 189)
-* Yahoo! <1>: STOXPRED. (line 6)
* Yahoo!: REMCONF. (line 6)
-* | (vertical bar), |& operator (I/O): TCP Connecting. (line 25)
+* Yahoo! <1>: STOXPRED. (line 6)
Tag Table:
-Node: Top2015
-Node: Preface5652
-Node: Introduction7027
-Node: Stream Communications8053
-Node: Datagram Communications9226
-Node: The TCP/IP Protocols10857
-Ref: The TCP/IP Protocols-Footnote-111541
-Node: Basic Protocols11698
-Ref: Basic Protocols-Footnote-113741
-Node: Ports13770
-Node: Making Connections15177
-Ref: Making Connections-Footnote-117738
-Ref: Making Connections-Footnote-217785
-Node: Using Networking17966
-Node: Gawk Special Files20284
-Node: Special File Fields22094
-Ref: table-inet-components25967
-Node: Comparing Protocols27287
-Node: File /inet/tcp27820
-Node: File /inet/udp28846
-Node: TCP Connecting29944
-Node: Troubleshooting32282
-Ref: Troubleshooting-Footnote-135334
-Node: Interacting35903
-Node: Setting Up38633
-Node: Email42127
-Node: Web page44453
-Ref: Web page-Footnote-147258
-Node: Primitive Service47455
-Node: Interacting Service50189
-Ref: Interacting Service-Footnote-159318
-Node: CGI Lib59350
-Node: Simple Server66311
-Ref: Simple Server-Footnote-174034
-Node: Caveats74135
-Node: Challenges75278
-Node: Some Applications and Techniques83957
-Node: PANIC86414
-Node: GETURL88132
-Node: REMCONF90755
-Node: URLCHK96231
-Node: WEBGRAB100066
-Node: STATIST104516
-Ref: STATIST-Footnote-1116224
-Node: MAZE116669
-Node: MOBAGWHO122853
-Ref: MOBAGWHO-Footnote-1136797
-Node: STOXPRED136852
-Node: PROTBASE151107
-Node: Links164188
-Node: GNU Free Documentation License167622
-Node: Index192761
+Node: Top2010
+Node: Preface5647
+Node: Introduction7022
+Node: Stream Communications8048
+Node: Datagram Communications9222
+Node: The TCP/IP Protocols10852
+Ref: The TCP/IP Protocols-Footnote-111536
+Node: Basic Protocols11693
+Ref: Basic Protocols-Footnote-113738
+Node: Ports13767
+Node: Making Connections15174
+Ref: Making Connections-Footnote-117732
+Ref: Making Connections-Footnote-217779
+Node: Using Networking17960
+Node: Gawk Special Files20283
+Node: Special File Fields22093
+Ref: table-inet-components25986
+Node: Comparing Protocols27295
+Node: File /inet/tcp27829
+Node: File /inet/udp28857
+Node: TCP Connecting29960
+Node: Troubleshooting32306
+Ref: Troubleshooting-Footnote-135365
+Node: Interacting35938
+Node: Setting Up38676
+Node: Email42179
+Node: Web page44511
+Ref: Web page-Footnote-147328
+Node: Primitive Service47526
+Node: Interacting Service50267
+Ref: Interacting Service-Footnote-159424
+Node: CGI Lib59456
+Node: Simple Server66420
+Ref: Simple Server-Footnote-174149
+Node: Caveats74250
+Node: Challenges75395
+Node: Some Applications and Techniques84093
+Node: PANIC86554
+Node: GETURL88278
+Node: REMCONF90911
+Node: URLCHK96398
+Node: WEBGRAB100247
+Node: STATIST104707
+Ref: STATIST-Footnote-1116444
+Node: MAZE116889
+Node: MOBAGWHO123088
+Ref: MOBAGWHO-Footnote-1137080
+Node: STOXPRED137135
+Node: PROTBASE151417
+Node: Links164533
+Node: GNU Free Documentation License167966
+Node: Index193086
End Tag Table
diff --git a/doc/gawkinet.texi b/doc/gawkinet.texi
index 1022323..12274d0 100644
--- a/doc/gawkinet.texi
+++ b/doc/gawkinet.texi
@@ -1764,7 +1764,7 @@ Here is the code:
@c file eg/network/coreserv.awk
#
# Juergen Kahrs, Juergen.Kahrs@@vr-web.de
-# with Arnold Robbins, arnold@@gnu.org
+# with Arnold Robbins, arnold@@skeeve.com
# September 2000
@c endfile
-----------------------------------------------------------------------
Summary of changes:
awklib/ChangeLog | 5 +
awklib/eg/network/coreserv.awk | 2 +-
awklib/extract.awk | 21 +-
doc/ChangeLog | 4 +
doc/gawkinet.info | 2563 ++++++++++++++++++++--------------------
doc/gawkinet.texi | 2 +-
6 files changed, 1294 insertions(+), 1303 deletions(-)
hooks/post-receive
--
gawk
| [Prev in Thread] |
Current Thread |
[Next in Thread] |
- [gawk-diffs] [SCM] gawk branch, gawk-4.1-stable, updated. gawk-4.1.0-721-gab40bfa,
Arnold Robbins <=